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API Reference

All core functionality lives in twenty-one subpackages, and every public name is reached through the one that owns it. The top-level phonometry package publishes those twenty-one and four names that belong to none of them: Signal, ReportMetadata, PhonometryWarning and __version__.

Note. This page is the curated quick table for the GitHub/PyPI audience: one row per public name, kept complete by a CI gate (scripts/check_api_reference.py). The full generated reference, with every signature, parameter table and cross-link, lives on the site: phonometry API reference.

Namespaces

The library is organized into twenty-one subpackages, and importing the namespace is the primary form used throughout the documentation:

from phonometry import aircraft

contour = aircraft.noise_contour(..., x=..., y=...)   # the shape of every call

Subpackage	Scope
phonometry.filters	Octave and fractional-octave filter banks, frequency weightings and time weighting, parametric EQ, IEC 61260-1 and IEC 61672-1 class verification
phonometry.signals	Levels (Leq, LAeq, percentiles), Welch and multitaper spectra, coherence, time-frequency, correlation, envelope, cepstrum, phase, synchronous averaging, test signals
phonometry.metrology	Calibration, GUM uncertainty and Monte Carlo, data qualification (stationarity, trends, peak statistics), the ISO 1683 reference values
phonometry.fluids	The state of the propagating medium: humid air from IEC 61094-2:2009 Annex F (CIPM-2007), with the conditions it was computed for and the domain its model states for itself
phonometry.solids	The elastic constants of a solid and the three longitudinal wave speeds that follow from them, named apart by the shape the wave travels in (beam, plate, unbounded), with the inverse of each and the h f_c a materials table prints
phonometry.io	Measurement audio files: WAV/BWF/RF64 read and write with bext provenance (EBU Tech 3285), headers-only info, block streaming, lossless conversion, calibration sidecar; FLAC, AIFF, Ogg/Opus and MP3 via the [audio] extra
phonometry.psychoacoustics	Two families: loudness (ISO 532-1 Zwicker, ISO 532-2 and ISO 532-3 Moore-Glasberg, ECMA-418-2, ISO 226 equal-loudness contours) and quality (sharpness, roughness, fluctuation strength, tonality, tone audibility, annoyance), plus the ERB scale both measure on
phonometry.speech	Speech Transmission Index (IEC 60268-16), Speech Intelligibility Index (ANSI S3.5), STOI and ESTOI
phonometry.hearing	Audiometric thresholds (ISO 7029/389-7), noise-induced hearing loss (ISO 1999), occupational exposure (ISO 9612)
phonometry.emission	Sound power (ISO 3740 family), sound intensity and the IEC 61043 instrument class it is measured with, vibration-based power
phonometry.room	Room acoustics (ISO 3382), impulse responses, open-plan, room-noise criteria, reverberation prediction, EN 12354-6
phonometry.building	Three subgroups: measurement (field, laboratory, survey and intensity methods with their ISO 717 ratings and ISO 12999 uncertainty), prediction (EN 12354 global and detailed models, facades, panels, apertures, plenums and resilient layers) and regulation (national codes)
phonometry.materials	Four families by what the material does: absorbers (ISO 354, ISO 11654, ISO 12999-2, impedance tube ISO 10534-2, airflow resistance ISO 9053, porous and multilayer models, Biot, slow-sound metamaterials), diffusers (Schroeder design, metadiffusers, scattering and diffusion ISO 17497), surfaces (in-situ road absorption ISO 13472) and resilient (dynamic stiffness EN 29052-1)
phonometry.vibration	Three families: structural (mobility ISO 7626, plate junctions, radiation, experimental SEA, transfer stiffness ISO 10846), human (ISO 2631/5349/8041 exposure and multiple shocks) and machinery (fault frequencies and condition monitoring)
phonometry.environment	Three subgroups: sources (CNOSSOS road and rail emission, wind-turbine apparent sound power), propagation (ISO 9613-1/-2, ground effect and barriers, refraction by ray tracing and the parabolic equation) and assessment (ISO 1996-1/-2 rating and measurement, impulsive prominence, RD 1367/2007)
phonometry.aircraft	EPNL (ICAO Annex 16), SAE ARP 5534 absorption, airport contours (ECAC Doc 29), rotorcraft (ECAC Doc 32)
phonometry.underwater	Three families: sources (ISO 17208 ship radiated noise, traffic, pile driving, wind and thermal ambient noise), propagation (closed-form and Weston propagation loss, normal modes, rays, Gaussian beams and the parabolic equation, seabed reflection, sound speed) and bioacoustics (marine-mammal audiograms and regulatory auditory weighting), over the ISO 18405 quantities and the sonar equation at the root
phonometry.electroacoustics	Distortion (IEC 60268-3 / AES17), transfer function and coherence, radiating piston
phonometry.noise_control	Reactive silencers (four-pole method), HVAC duct attenuation, machine-enclosure insertion loss
phonometry.broadcast	Programme loudness and true peak (ITU-R BS.1770-5, EBU R 128 with Tech 3341/3342)
phonometry.simulation	2D acoustic FDTD wave simulation (staggered grid, sources, probes, impedance boundaries, obstacles)

The table below lists each name unqualified, the way its own page titles it; the usage snippet shows the namespace to import and call it through. The module paths of every earlier layout were removed in 4.0 along with the shims that served them, so phonometry.metrology.levels, phonometry.environmental and the rest of the pre-4.0 spellings raise ModuleNotFoundError. The paths in force are the ones the generated reference documents, one page per module.

Reading the input column. Every function that consumes a recording accepts a phonometry.io.Signal wherever the table writes a signal argument, and then fs is optional: the object carries it, and an explicit value that disagrees with it raises rather than overriding it. A bare array still requires fs by name. A calibrated Signal is analysed in pascals, with four documented exemptions (the EBU R 128 family, the dbfs=True paths, quantities that are not pressures, and metrology.sensitivity, which is what produces a calibration factor). Each function's own page states which of these applies to it.

Name	Type	Description (Inputs)	Usage Snippet (Outputs)
octave_filter	function	High-level analysis. • x: Signal array • fs: Sample rate [Hz] • fraction: 1, 3, etc. (Default: 1) • order: Filter order (Default: 6) • limits: [f_min, f_max] (Default: [12, 20000]) • sigbands: Return time signals (Default: False) • detrend: Remove DC offset (Default: True) • mode: 'rms' or 'peak' (Default: 'rms') • nominal: IEC 61260-1 nominal labels (Default: False) • design: FilterDesign (family, ripple, attenuation, decimation) • calibration: LevelCalibration (factor, dBFS) • response_plot: ResponsePlot (show, file)	r = filters.octave_filter(x, fs, ...) • r.levels: band levels [dB] • r.frequencies: band centres [Hz] • r.bands: one waveform per band, or None With sigbands=True: bands = filters.octave_filter(x, fs, sigbands=True).require_bands() Calibrated usage: filters.octave_filter(x, fs, calibration=filters.LevelCalibration(factor=0.05)).levels
OctaveFilterResult	dataclass	What a filter bank gives back for one signal. • levels: band levels [dB], (bands,) or (channels, bands), None when the call asked for no level • frequencies: one band centre per level, exact or IEC 61260-1 nominal labels • bands: one waveform per band, None unless sigbands=True • .require_levels() / .require_bands(): the value, or a ValueError naming the argument that was missing • .plot(): the band spectrum on a log frequency axis	r = filters.octave_filter(x, fs, fraction=3) r.levels[r.frequencies.index(1000.0)] • ax = r.plot()
OctaveFilterBank	class	Efficient bank implementation. • fs: Sample rate [Hz] • fraction: 1, 3, etc. • order: Filter order • limits: [f_min, f_max] (Default: [12, 20000]) • design: FilterDesign (family, ripple, attenuation, decimation) • calibration: LevelCalibration (factor, dBFS) • block_processing: BlockProcessing (stateful, steady_ic) • response_plot: ResponsePlot (show, file)	bank = filters.OctaveFilterBank(fs=48000, fraction=3, order=6, design=filters.FilterDesign(filter_type='butter')) r = bank.filter(x, sigbands=False, mode='rms', detrend=True, zero_phase=False) • r.levels, r.frequencies, r.bands (an OctaveFilterResult) • bank: Instance of the filter bank • bank.freq / bank.freq_d / bank.freq_u / bank.sos: computed properties
FilterDesign	dataclass	How the band filters are designed. • filter_type: 'butter', 'cheby1', 'cheby2', 'ellip', 'bessel' (Default: 'butter') • ripple: Passband ripple [dB] (for cheby1/ellip; Default: 0.1) • attenuation: Stopband attenuation [dB] (Default: 72; cheby2 needs >= 70 dB for class 1) • resample: Multirate decimation (Default: True)	OctaveFilterBank(48000, 3, design=filters.FilterDesign(filter_type='cheby2'))
LevelCalibration	dataclass	How band energy becomes a level. • factor: Sensitivity multiplier, Pa per digital unit (Default: 1.0) • dbfs: Output in dBFS instead of dB SPL (Default: False)	octave_filter(x, fs, calibration=filters.LevelCalibration(factor=0.05))
BlockProcessing	dataclass	Filter state carried between calls. • stateful: Carry filter state between calls (Default: False) • steady_ic: Steady-state initial conditions (Default: False)	OctaveFilterBank(48000, 1, design=filters.FilterDesign(resample=False), block_processing=filters.BlockProcessing(stateful=True))
ResponsePlot	dataclass	Response plot drawn while designing. • show: Show the plot (Default: False) • file: Path to save the plot (Default: None)	OctaveFilterBank(48000, 3, response_plot=filters.ResponsePlot(show=True))
OctaveFilterBank.spectrogram	method	Band levels over time. • x: Signal array (1D or 2D) • window_time: Window length [s] (Default: 0.125) • overlap: Fraction in [0, 1) (Default: 0.5) • mode: 'rms' or 'peak' • zero_phase: Group-delay-free frames (Default: False)	levels, freq, times = bank.spectrogram(x) • levels: (bands, frames) or (channels, bands, frames) • times: window centers [s]
weighting_filter	function	Acoustic weighting. • x: Signal array • fs: Sample rate [Hz] • curve: 'A', 'C' (IEC 61672-1), 'B' (ANSI S1.4-1983, historical), 'D' (withdrawn IEC 537, aircraft), 'G' (ISO 7196 infrasound), 'AU' (IEC 61012), '468' (ITU-R BS.468-4 psophometric) or 'Z' (Default: 'A') • high_accuracy: fit the analog prototype at fs instead of transforming it blind, for IEC class 1 accuracy at every rate (Default: True; '468' requires it)	y = filters.weighting_filter(x, fs, curve='A') • y: weighted signal
WeightingFilter	class	Reusable weighting filter. • fs: Sample rate [Hz] • curve: 'A', 'B', 'C', 'D', 'G', 'AU', '468' or 'Z' • stateful: Block processing (Default: False) • steady_ic: Steady-state initial conditions (Default: False) • high_accuracy: Fitted design, independent of stateful (Default: True; '468' refuses False)	wf = filters.WeightingFilter(fs, 'A') y = wf.filter(x)
time_weighting	function	Energy capture. • x: Raw signal array (squared internally; time is the last axis) • fs: Sample rate [Hz] • mode: 'fast', 'slow', or 'impulse' • initial_state: None, 'zero', 'first', scalar, or array (Default: None)	env = filters.time_weighting(x, fs, mode='fast') • env: energy envelope (Mean Square), same shape as x
TimeWeightedEnvelope	dataclass	Exponentially averaged mean square of a record, with its rate. • mean_square [Pa² when calibrated], fs [Hz], mode, calibrated • stands in for the bare array it replaced (np.asarray, indexing, shape) • returned by time_weighting/TimeWeighting.process for a Signal input; a mean square is not a pressure record, so it is not a Signal	env = filters.time_weighting(filters.weighting_filter(sig, curve='A'), mode='fast') env.plot() # the L_pAF trace in dB
TimeWeighting	class	Stateful time weighting. • fs: Sample rate [Hz] • mode: 'fast', 'slow', 'impulse' (Default: 'fast')	tw = filters.TimeWeighting(fs, mode='fast') env = tw.process(block) per block tw.reset() to start over
leq	function	Equivalent level (Leq). • x: Signal array (1D or 2D) or a phonometry.io.Signal • calibration_factor: Sensitivity multiplier (Default: None: a calibrated Signal's factor, else 1.0; explicit wins) • dbfs: Output in dBFS (Default: False)	level = signals.leq(x, calibration_factor=s) • level: Scalar (1D) or per-channel array (2D)
laeq	function	A-weighted Leq (LAeq). • x: Signal array (1D or 2D) or a phonometry.io.Signal • fs: Sample rate [Hz] (taken from x when x is a Signal) • calibration_factor / dbfs: as leq	level = signals.laeq(x, fs, calibration_factor=s) • level: Scalar (1D) or per-channel array (2D)
ln_levels	function	Statistical levels (LN). • x: Signal array (1D or 2D) or a phonometry.io.Signal • fs: Sample rate [Hz] (taken from x when x is a Signal) • n: Exceedance percentiles (Default: (10, 50, 90)) • mode: 'fast', 'slow', 'impulse' (Default: 'fast') • weighting: any weighting_filter curve, 'A', 'B', 'C', 'D', 'G', 'AU', '468' or 'Z', or None (Default: None) • calibration_factor / dbfs: as leq	stats = signals.ln_levels(x, fs, n=(10, 50, 90), weighting='A') • stats: Dict {10: L10, 50: L50, 90: L90}
lc_peak	function	C-weighted peak (LCpeak). • x: Signal array (1D or 2D) or a phonometry.io.Signal • fs: Sample rate [Hz] (taken from x when x is a Signal) • calibration_factor: as leq • dbfs: 0 dBFS = full-scale peak (amplitude 1.0), unlike the RMS reference of leq • oversample: HF inter-sample peak recovery (Default: 8; 1 = on-grid, under-reads up to ~1.15 dB at 48 kHz)	peak = signals.lc_peak(x, fs) • IEC 61672-1 §5.13; verified against Table 5
sel	function	Sound exposure level (SEL/LAE). • x: Whole-event signal (1D or 2D) or a phonometry.io.Signal • fs: Sample rate [Hz] (taken from x when x is a Signal) • weighting: any weighting_filter curve, 'A', 'B', 'C', 'D', 'G', 'AU', '468' or 'Z', or None (Default: None) • calibration_factor / dbfs: as leq	lae = signals.sel(x, fs, weighting='A') • Event level normalized to 1 s
sound_exposure	function	A-weighted exposure E (IEC 61252). • x: Signal (1D or 2D) or a phonometry.io.Signal • fs: Sample rate [Hz] (taken from x when x is a Signal) • duration_hours: exposure period represented (Default: recording length) • calibration_factor	E = signals.sound_exposure(x, fs, duration_hours=8) • E: Pa²·h
lex_8h	function	Daily exposure LEX,8h / LEP,d. • Same params as sound_exposure	lex = signals.lex_8h(x, fs, duration_hours=4) • Normalized 8 h level [dB]
loudness_zwicker	function	Zwicker loudness (ISO 532-1:2017). • x: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] • field: 'free' or 'diffuse' (Default: 'free') • stationary: Clause 5 stationary method (Default: False) • time_skip: seconds excluded from the stationary mean square (Annex B.1 uses 0.2 s; Default: 0.0) • calibration_factor: Digital units to Pa (Default: 1.0)	res = psychoacoustics.loudness_zwicker(x, fs) • ZwickerLoudness; time-varying runs add N5/N10 and the 500 Hz N(t) trace
loudness_zwicker_from_spectrum	function	Stationary loudness from band levels. • levels: 28 one-third-octave levels, 25 Hz-12.5 kHz [dB SPL] • field: 'free' or 'diffuse' (Default: 'free')	res = psychoacoustics.loudness_zwicker_from_spectrum(levels) • res.loudness [sone], res.loudness_level [phon]
ZwickerLoudness	dataclass	Loudness result. • loudness: N [sone] • loudness_level: LN [phon] • specific: N′(z), 240 bins of 0.1 Bark • n5 / n10: percentile loudness (time-varying only) • times / loudness_vs_time: 500 Hz trace • field: sound field assumed ('free'/'diffuse')	res.loudness, res.n5 • Time-varying fields are None for stationary results
sharpness_din	function	Sharpness in acum (DIN 45692). • x: Signal (1D) • fs: Sample rate [Hz] • field: 'free' or 'diffuse' (Default: 'free') • method: 'din', 'aures' or 'bismarck' (Default: 'din') • calibration_factor: Digital units to Pa (Default: 1.0)	s = psychoacoustics.sharpness_din(x, fs) • s: sharpness [acum]
sharpness_din_from_specific	function	Sharpness from a specific-loudness pattern. • specific: N′(z), 240 values at 0.1 Bark (e.g. ZwickerLoudness.specific) • method: 'din', 'aures' or 'bismarck' (Default: 'din')	s = psychoacoustics.sharpness_din_from_specific(res.specific) • s: sharpness [acum]
erb_bandwidth	function	Auditory-filter equivalent rectangular bandwidth ERB_N (Glasberg & Moore 1990; Moore 6e p. 76). • frequency [Hz] (scalar or array, ≥ 0) • ERB_N = 24.673(0.004368 f + 1) [Hz]	erb_bandwidth(1000.0) # 132.4
cam_from_frequency / frequency_from_cam	function	The Cam (ERB_N-number) frequency scale, one unit per auditory-filter width. • cam_from_frequency(f) = 21.366 log10(0.004368 f + 1) [Cam] • frequency_from_cam(i): the exact inverse [Hz]	cam_from_frequency(1000.0) # 15.59 frequency_from_cam(15.59)
ERB_C1 / ERB_C2 / CAM_C	constant	Constants of the ERB_N fit shared with the ISO 532-2 loudness model. • ERB_C1 = 24.673 [Hz], ERB_C2 = 0.004368 [1/Hz], CAM_C = 21.366 [Cam]	ERB_C1 * (ERB_C2 * f + 1)
loudness_moore_glasberg	function	Moore-Glasberg loudness (ISO 532-2:2017). • x: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] • field: 'free', 'diffuse' or 'eardrum' (Default: 'free') • presentation: 'binaural'/'diotic' or 'monaural' (Default: 'binaural')	res = psychoacoustics.loudness_moore_glasberg(x, fs) • MooreGlasbergLoudness (roex excitation pattern)
loudness_moore_glasberg_from_spectrum	function	Exact loudness from sinusoidal components (ISO 532-2 §5.2/5.4). • components: sequence of (frequency [Hz], level [dB SPL]) pairs • field: 'free'/'diffuse'/'eardrum' (Default: 'free') • presentation: (Default: 'binaural')	res = psychoacoustics.loudness_moore_glasberg_from_spectrum([(1000.0, 40.0)]) • 1 kHz/40 dB → 1.000 sone
loudness_moore_glasberg_from_third_octave	function	Loudness from 29 one-third-octave band levels (ISO 532-2 §5.5). • band_levels: 29 levels, 25 Hz–16 kHz [dB SPL] • field / presentation: as above	res = psychoacoustics.loudness_moore_glasberg_from_third_octave(levels) • MooreGlasbergLoudness
MooreGlasbergLoudness	dataclass	Moore-Glasberg loudness result. • loudness: N [sone] • loudness_level: LN [phon] • specific: N′(i), 372 bins of 0.1 Cam • erb_number / centre_frequencies: Cam / Hz axes • field / presentation • .plot(): specific loudness N′(i) over Cam	res.loudness, res.loudness_level
loudness_moore_glasberg_time	function	Time-varying loudness (ISO 532-3:2023). • signal: Calibrated Pa; 1D (diotic) or (n, 2) ears • fs: Sample rate [Hz] • field: 'free'/'diffuse'/'eardrum' (Default: 'free') • presentation: (Default: 'binaural') • percentiles: exceedance % (Default: (1,5,10,50,90,95))	res = psychoacoustics.loudness_moore_glasberg_time(x, fs) • MooreGlasbergTimeVaryingLoudness
MooreGlasbergTimeVaryingLoudness	dataclass	Time-varying loudness result. • times: 1 ms grid [s] • short_term_loudness / long_term_loudness: S′(t)/S″(t) [sone] • short_term_loudness_level / long_term_loudness_level [phon] • n_max / loudness_level_max: peak long-term loudness • percentiles: dict {percent: sone} • .plot(): STL and LTL vs time	res.n_max, res.percentiles[5.0]
loudness_ecma	function	Sottek Hearing Model loudness (ECMA-418-2:2025). • signal_in: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] (resampled to 48 kHz) • field: 'free' or 'diffuse' (Default: 'free')	res = psychoacoustics.loudness_ecma(x, fs) • EcmaLoudness; 1 kHz/40 dB ≈ 1 sone_HMS
EcmaLoudness	dataclass	Sottek loudness result. • loudness: N [sone_HMS] • specific_loudness: N′(z), 53 Bark_HMS bands • bark / centre_frequencies: z / Hz axes • times / loudness_vs_time: N(l) at 187.5 Hz • field • .plot(): N′(z) + N(l)	res.loudness, res.specific_loudness
tonality_ecma	function	Sottek tonality (ECMA-418-2:2025). • signal_in: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] (resampled to 48 kHz) • field: 'free' or 'diffuse' (Default: 'free') • f_low / f_high: optional user band [Hz] (Default: None)	res = psychoacoustics.tonality_ecma(x, fs) • EcmaTonality; 1 kHz/40 dB ≈ 1 tu_HMS
EcmaTonality	dataclass	Sottek tonality result. • tonality: T [tu_HMS] • specific_tonality: T′(z), 53 bands • tonal_frequencies: f_ton,z per band [Hz] • bark / centre_frequencies • times / tonality_vs_time / tonal_frequency_vs_time: T(l), f_ton(l) • field • .plot(): T′(z) + T(l)	res.tonality, res.tonal_frequencies
roughness_ecma	function	Sottek roughness (ECMA-418-2:2025), new capability. • signal_in: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] (resampled to 48 kHz) • field: 'free' or 'diffuse' (Default: 'free')	res = psychoacoustics.roughness_ecma(x, fs) • EcmaRoughness; 1 kHz/70 Hz/100 %-AM/60 dB ≈ 1 asper
EcmaRoughness	dataclass	Sottek roughness result. • roughness: R [asper] (90th percentile of R(l50)) • specific_roughness: R′(z), 53 bands • bark / centre_frequencies • times / roughness_vs_time: R(l50) at 50 Hz • specific_roughness_vs_time: (n_times, 53) • field • .plot(): R(l50) + specific-roughness heatmap	res.roughness, res.specific_roughness
fluctuation_strength_ecma	function	Sottek fluctuation strength (ECMA-418-2:2025 Clause 9), new capability. • signal_in: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] (resampled to 48 kHz) • field: 'free' or 'diffuse' (Default: 'free')	res = psychoacoustics.fluctuation_strength_ecma(x, fs) • EcmaFluctuationStrength; 1 kHz/4 Hz/100 %-AM/60 dB ≈ 1 vacil_HMS
EcmaFluctuationStrength	dataclass	Sottek fluctuation-strength result. • fluctuation_strength: F [vacil_HMS] (90th percentile of F(l50)) • specific_fluctuation_strength: F′(z), 53 bands • bark / centre_frequencies • times / fluctuation_strength_vs_time: F(l50) at 50 Hz • specific_fluctuation_strength_vs_time: (n_times, 53) • field • .plot(): F(l50) + specific-fluctuation-strength heatmap	res.fluctuation_strength, res.specific_fluctuation_strength
psychoacoustic_annoyance	function	Psychoacoustic annoyance PA (Fastl & Zwicker Eqs 16.2–16.4), exact model. • n5: percentile loudness N5 [sone] • sharpness S [acum] • fluctuation_strength F [vacil] • roughness R [asper]	res = psychoacoustics.psychoacoustic_annoyance(30, 2.0, 0.5, 0.3) • PsychoacousticAnnoyanceResult; res.annoyance == 37.0478
psychoacoustic_annoyance_from_signal	function	PA from a calibrated signal (convenience, engineering estimate). • x: Calibrated signal in Pa (1D) • fs: Sample rate [Hz] • field: 'free' or 'diffuse' (Default: 'free') • calibration_factor (Default: 1.0) Mixes Zwicker N5/S + Sottek R + Osses F.	res = psychoacoustics.psychoacoustic_annoyance_from_signal(x, fs) • PsychoacousticAnnoyanceResult
PsychoacousticAnnoyanceResult	dataclass	Psychoacoustic annoyance result. • annoyance: PA • n5 [sone] / sharpness [acum] / fluctuation_strength [vacil] / roughness [asper]: the four inputs • w_s: sharpness weighting wS • w_fr: roughness/fluctuation weighting wFR • .plot(): term-contribution bar	res.annoyance, res.w_s, res.w_fr
fluctuation_strength_am_noise	function	Fluctuation strength of AM broadband noise (Fastl & Zwicker Eq. 10.2), exact closed form. • level_db L [dB] • modulation_factor m (0–1) • mod_frequency fmod [Hz]	fluctuation_strength_am_noise(60, 1.0, 4.0) # 3.6943 vacil
fluctuation_strength	function	Fluctuation strength F (Osses 2016 signal model), no numeric standard, free-field. • signal_in: Calibrated signal in Pa (1D) • fs: Sample rate [Hz]	res = psychoacoustics.fluctuation_strength(x, fs) • FluctuationStrengthResult; 1 kHz/60 dB/m=1/4 Hz AM ≈ 1 vacil
FluctuationStrengthResult	dataclass	Fluctuation strength result. • fluctuation_strength: F [vacil] • specific: F′(z), 47 values • bark_axis: z [Bark], 47 values • time_dependent: F(t) per frame • .plot(): specific F′(z) over the Bark axis	res.fluctuation_strength, res.specific
equal_loudness_contour	function	ISO 226:2023 equal-loudness contour. • phon: Loudness level, 20-90 phon	freqs, spl = psychoacoustics.equal_loudness_contour(40.0) • SPL at the 29 preferred frequencies
equal_loudness_contours	function	ISO 226:2023 equal-loudness contour family (plottable). • phons: Loudness levels [phon] (Default: 20-90 in 10-phon steps) • frequencies: Grid [Hz] (Default: the 29 preferred)	res = psychoacoustics.equal_loudness_contours() • EqualLoudnessContours; res.plot()
EqualLoudnessContours	dataclass	Equal-loudness contour family result. • frequencies: grid [Hz] • phons: contour levels [phon] • contours: SPL, (len(phons), len(frequencies)) [dB] (nan where undefined) • threshold: hearing threshold $T_f$ [dB] • .plot(): the iconic ISO 226 chart	res.contours, res.threshold
loudness_level	function	Loudness level of a pure tone (phon). • spl: Tone SPL [dB] • frequency: One of the 29 Table 1 frequencies [Hz]	phon = psychoacoustics.loudness_level(73.0, 63.0)
hearing_threshold	function	Threshold of hearing (ISO 226 Table 1). • (no parameters)	freqs, tf = psychoacoustics.hearing_threshold()
tone_to_noise_ratio	function	Tone-to-noise ratio (ECMA-418-1 §11). • x: Signal (1D) • fs: Sample rate [Hz] • tone_freq: Tone to assess [Hz] (Default: highest peak) • resolution_hz: FFT bin spacing (Default: 1.0)	r = psychoacoustics.tone_to_noise_ratio(x, fs) • ToneAssessment(frequency, ratio_db, criterion_db, prominent)
prominence_ratio	function	Prominence ratio (ECMA-418-1 §12). • Same params as tone_to_noise_ratio	r = psychoacoustics.prominence_ratio(x, fs, tone_freq=1000) • ToneAssessment(...)
ToneAssessment	dataclass	Tone prominence verdict. • frequency: Assessed tone [Hz] • ratio_db: TNR or PR [dB] • criterion_db: Prominence limit at that frequency [dB] • prominent: bool	r = psychoacoustics.tone_to_noise_ratio(x, fs) if r.prominent: ...
tone_audibility	function	Tone audibility ΔL = LT−LG−av (ISO/PAS 20065 Formulae 12–14). • tone_level LT, mean_narrowband_level LS [dB] • tone_frequency fT [Hz], line_spacing Δf [Hz]	tone_audibility(67.96, 49.22, 137.3, 2.7) # 5.01 dB
assess_tones	function	Audibility of a spectrum's tones (ISO/PAS 20065). • tone_frequencies [Hz], tone_levels LT, mean_narrowband_levels LS [dB] • line_spacing Δf [Hz] • extended_uncertainties: attach the Clause 5.4 U per tone (Default: True)	res = psychoacoustics.assess_tones(fT, LT, LS, 2.7) • ToneAudibilityResult
critical_bandwidth_engineering	function	Critical bandwidth Δfc about a tone (Formula 2). • tone_frequency fT [Hz]	critical_bandwidth_engineering(137.3) # 101.36 Hz
critical_band_corners	function	Corner frequencies (f₁, f₂) of the critical band (Formulae 3–5). • tone_frequency fT [Hz]	f1, f2 = psychoacoustics.critical_band_corners(137.3)
critical_band_level	function	Masking-noise level LG = LS+10lg(Δfc/Δf) (Formula 12). • mean_narrowband_level LS [dB], tone_frequency fT, line_spacing Δf [Hz]	critical_band_level(49.22, 137.3, 2.7) # 64.97 dB
masking_index	function	Masking index av = −2−lg[1+(f/502)²·⁵] (Formula 13). • frequency f [Hz]	masking_index(137.3) # -2.02 dB
audibility_from_levels	function	ΔL = LT − LG − av (Formula 14). • tone_level LT, critical_band_level LG, masking_index av [dB]	audibility_from_levels(67.96, 64.98, -2.02) # 5.0 dB
energy_sum_level	function	Energy sum of lines with window correction (Formulae 7/8). • line_levels Li [dB]; a single line (K = 1) takes its level unchanged (Formula 7, no correction) • effective_bandwidth_factor Δfe/Δf (Default: 1.5, Hanning; K > 1 only)	energy_sum_level([80, 80]) # 81.25 dB
mean_narrowband_level	function	Masking-noise level LS from a critical-band spectrum (Formula 6, iterative Annex D). • levels Li [dB], frequencies [Hz] • tone_frequency fT [Hz] • effective_bandwidth_factor (Default: 1.5)	mean_narrowband_level(levels, freqs, 137.3) # 49.22 dB
tone_level	function	Tone level LT from the tonal lines about a peak (Formulae (7)/(8): single lines take (7), without the Hanning bandwidth correction). • levels Li [dB], frequencies [Hz] • tone_frequency fT [Hz], mean_narrowband_level LS [dB] • effective_bandwidth_factor (Default: 1.5)	tone_level(levels, freqs, 137.3, ls) # 67.96 dB
audibility_uncertainty / mean_audibility_uncertainty	function	Extended uncertainty U of the audibility (ISO/PAS 20065 Clause 5.4/6, 90 % bilateral). • per tone: audibility_uncertainty(tone_line_levels, noise_line_levels, tone_frequency, line_spacing) • mean: U of the energy-averaged audibility over the per-spectrum (ΔL, U) pairs Mandatory when fewer than 12 spectra are averaged (Clause 6)	u = psychoacoustics.audibility_uncertainty(lt_lines, ls_lines, 137.3, 2.7) • U [dB]
analyze_spectrum	function	Detect & rate the audible tones of a spectrum (Clause 5.3.8 + distinctness 5.3.4), incl. Step 3 same-band FG combination (Formula 17). • levels Li [dB], frequencies [Hz] • line_spacing Δf [Hz] • effective_bandwidth_factor (Default: 1.5)	res = psychoacoustics.analyze_spectrum(levels, freqs, 2.7) • ToneAudibilityResult of detected tones + FG entries (group_sizes)
combined_tone_level	function	Multi-tone FG combined level (Formula 17). • levels Li [dB], frequencies [Hz] • tone_frequencies [Hz], mean_narrowband_levels LS [dB] • effective_bandwidth_factor (Default: 1.5)	combined_tone_level(lv, f, [118.4,137.3,158.8], ls) # 72.15 dB
two_tone_separation_frequency	function	Two-tone separation threshold fD = 21·10^(1.2·|lg(fT/212)|^1.8) Hz (Formula 19). • tone_frequency fT [Hz] (more prominent tone)	two_tone_separation_frequency(212.0) # 21.0 Hz
resolve_tones_separately	function	Rate two tones <1000 Hz separately vs combined (Formulae 18/19). • tone1_frequency, tone2_frequency [Hz] • audibility1, audibility2 ΔL [dB]	resolve_tones_separately(200., 260., 3., 2.) # True
mean_audibility	function	Energy-mean mean audibility over spectra (Formula 20). • decisive_audibilities ΔLj [dB]; no-tone spectra use −10 dB	mean_audibility([9.18, 6.04, 7.46]) # dB
ToneAudibilityResult	dataclass	Tonal audibility of a spectrum's tones (ISO/PAS 20065). • audibilities ΔL, critical_band_levels LG, masking_indices av [dB] • critical_bandwidths Δfc, lower_corners/upper_corners [Hz] • audible: ΔL > 0 mask • extended_uncertainties: Clause 5.4 U per tone [dB] • group_sizes: 1 = single tone, N ≥ 2 = Step 3 FG entry (None from assess_tones) • decisive_audibility / decisive_frequency • .plot(): per-tone ΔL vs frequency	res.decisive_audibility, res.audible
HANNING_BANDWIDTH_FACTOR	float	Hanning effective-bandwidth factor Δfe/Δf (ISO/PAS 20065 Annex A). 1.5	HANNING_BANDWIDTH_FACTOR # 1.5
NO_TONE_AUDIBILITY	float	Audibility reported when no tone is found [dB] (ISO/PAS 20065 Formula 21). -10.0	NO_TONE_AUDIBILITY # -10.0
sti_from_impulse_response	function	Full STI, indirect method (IEC 60268-16 Ed. 5). • ir: Impulse response (1D) • fs: Sample rate [Hz] (>= 22500) • snr: SNR [dB], scalar or 7 bands (Default: None) • levels: 7 speech band levels [dB SPL]; enables masking + reception threshold (Default: None) • ambient: 7 noise band levels [dB SPL]; requires levels	res = speech.sti_from_impulse_response(ir, fs, snr=25.0) • STIResult with `mtf$ (7 \times 14)
$stipa`	function	STIPA direct method (Annex B). • x: Recorded STIPA signal (1D), 15-25 s • fs: Sample rate [Hz] (>= 22500) • reference: Measured source signal instead of the nominal m = 0.55 (Default: None) • levels / ambient: as sti_from_impulse_response • warns (UserWarning) if the recording is < 15 s (STI biased low)	res = speech.stipa(recording, fs) • STIResult with `mtf$ (7 \times 2)
$stipa_signal`	function	STIPA test-signal generator (A.4/A.6.1). • fs: Sample rate [Hz] (>= 22500) • seconds: Duration [s] (Default: 18.0) • level_db: RMS level [dB SPL] (Default: None → RMS 0.1) • seed: Pink-noise seed (Default: None)	sig = speech.stipa_signal(48000, seconds=18.0) • 1D test signal, Ed. 5 male spectrum
sti_adjusted_for_levels	function	Occupancy-noise and speech-level adjustment (Ed. 4 Annex M). • mtf$: \text{measured} \text{m} \text{matrix} (7 \times \text{n}), \text{noise} \text{and} \text{masking} \text{included}<\text{br}>• $measured_levels: 7 band levels [dB SPL] during the measurement • measured_ambient: same, background noise (Default: None) • operational_levels: 7 band levels [dB SPL] of the condition simulated • operational_ambient: same, occupancy noise (Default: None)	res = speech.sti_adjusted_for_levels(mtf, measured_levels=lm, measured_ambient=nm, operational_levels=lo, operational_ambient=no) • STIResult at the operational levels
STIResult	dataclass	STI result. • sti: 0 to 1 • mti: band indices (7,) • mtf$: \text{corrected} \text{m} \text{values} (7 \times 14 \text{or} 7 \times 2)<\text{br}>• $band_levels / ambient_levels: levels used or None • rating: Annex F letter 'A+'…'U' • .adjusted_for_levels(operational_levels=…, operational_ambient=…): the same result at another condition (Annex M)	res = speech.stipa(x, fs) print(res.sti, res.rating)
sound_intensity	function	p-p sound intensity (IEC 61043). • p1, p2: Microphone signals [Pa], equal length • fs: Sample rate [Hz] • spacing: Microphone separation Δr [m] • density: Air density (Default: 1.204) • speed_of_sound: Speed of sound (Default: 343.0) • fraction: None, 1 or 3 (Default: None) • limits: [f_min, f_max] (Default: [12, 20000]) • bias_correct: undo finite-difference under-read of band/broadband totals near max_valid_frequency (Default: False)	res = emission.sound_intensity(p1, p2, fs, spacing=0.012, fraction=3) • IntensityResult
plot_pp_probe_geometry	function	Face-to-face p-p probe to scale. • spacing dr [m] (Default: 12 mm) • language	plot_pp_probe_geometry() • Also IntensityResult.plot_geometry()
IntensityResult	dataclass	Intensity result. • Per band (with fraction): frequencies, intensity [W/m²], intensity_level, pressure_level, pressure_intensity_index, direction (±1), bias_correction • Broadband: total_* counterparts • max_valid_frequency: 0.1·c/Δr	res.total_intensity_level res.total_direction
field_indicators	function	ISO 9614-1 Annex A field indicators. • pressure_levels: Lpi per position [dB] • normal_intensity: Signed Ini per position [W/m²] • temporal_intensity: optional M short-time Ink samples at one fixed position, filling f1	fi = emission.field_indicators(lp, i_n) • FieldIndicators(f2, f3, f4, f1)
FieldIndicators	dataclass	ISO 9614-1 Annex A indicators. • f1: temporal variability indicator (Eq. A.1), or None when no temporal_intensity was given • f2: surface pressure-intensity indicator (Eq. A.3) • f3: negative partial power indicator (Eq. A.6) • f4: field non-uniformity indicator (Eq. A.8) • f3 − f2 > 0 reveals negative partial power • .field_is_stationary(limit=0.6): Table B.3 check on F1	fi.f2, fi.f3, fi.f4 • Criteria: Ld > F2, N > C·F4²
dynamic_capability_index	function	Dynamic capability Ld (ISO 9614-1 §3.12). • pressure_residual_intensity_index: δpI0 [dB] • bias_error_factor: K [dB] (Default: 10.0)	ld = emission.dynamic_capability_index(18.0) • Adequate when Ld > F2 (criterion 1)
temporal_variability_indicator	function	ISO 9614-1 temporal variability F1 (Eq. A.1). • short_time_intensity: M short-time-averaged signed In samples at one fixed position [W/m²], 1D (samples,) or 2D (samples, bands)	f1 = emission.temporal_variability_indicator(samples) • Coefficient of variation of the M samples; Table B.3 acts above 0.6
TEMPORAL_VARIABILITY_LIMIT	constant	ISO 9614-1 Table B.3 limit on F1 (0.6): above it the field is too variable and action code (e) applies	fi.field_is_stationary(TEMPORAL_VARIABILITY_LIMIT)
residual_index_limits	function	IEC 61043 Table 2 minimum δpI0. • device: 'probe', 'processor' or 'instrument' (Default: 'instrument') • spacing: microphone separation [m] (Default: 0.025; Note 1 adds 10 lg(x/25)) • frequencies: bands to report (Default: all 22, 50 Hz to 6.3 kHz)	f, c1, c2 = emission.residual_index_limits("probe", spacing=0.012) • (frequencies, class1, class2) minima [dB]
verify_intensity_class	function	IEC 61043 Table 2 class check. • residual_index: measured δpI0 per band [dB] • frequencies: band centres [Hz] • keyword-only: device, spacing, as above	res = emission.verify_intensity_class(d, f, spacing=0.012) res.report("iec61043.pdf") • IntensityInstrumentComplianceResult
IntensityInstrumentComplianceResult	dataclass	IEC 61043 instrument class verdict. • overall_class: loosest class every band meets (1/2), or None • bands, frequencies, residual_index, limit_class1, limit_class2 • spacing, spacing_offset_db, device, range_limited • .binding_margin() / .failing_bands() / .reference_class() • .phase_mismatch(speed_of_sound=343.0): equivalent channel phase error per band [deg] • .plot(): measured δpI0 over the two Table 2 masks • .report(path, *, metadata=None): one-page PDF fiche	res.overall_class, res.binding_margin()
instrument_class_from_components	function	IEC 61043 clause 8 combination rule. • probe_class, processor_class: 1 or 2	instrument_class_from_components(1, 2) • 1 only when both are class 1, else 2
phase_mismatch_from_residual_index	function	δpI0 → channel phase mismatch. • residual_index: δpI0 [dB] • frequency [Hz], spacing [m], speed_of_sound (Default: 343.0) • φs = kd·10^(−δpI0/10)	phase_mismatch_from_residual_index(20.0, 1000.0, 0.025) • 0.26 degrees
residual_index_from_phase_mismatch	function	Channel phase mismatch → δpI0. • phase_mismatch: φs [deg], > 0 • frequency [Hz], spacing [m], speed_of_sound (Default: 343.0) • δpI0 = 10 lg(kd/φs)	residual_index_from_phase_mismatch(0.05, 1000.0, 0.012) • 24.0 dB
CalibrationWarning	warning class	Unreliable calibration recording. Emitted by sensitivity (with fs given and validate=True) when the tone is unstable (IEC 60942 limit) or too short	warnings.simplefilter("error", CalibrationWarning)
lden	function	Day-evening-night level (ISO 1996-1 §3.6.4). • lday/levening/lnight: LAeq per period [dB] • hours: Period durations (Default: (12, 4, 8))	l = environment.lden(63.2, 58.1, 51.4)
ldn	function	Day-night level (ISO 1996-1 §3.6.5). • lday/lnight: LAeq per period [dB] • hours: Default (15, 9)	l = environment.ldn(63.2, 51.4)
composite_rating_level	function	Whole-day composite rating (ISO 1996-1 §6.5). • periods: list of (level_db, hours, adjustment_db) summing 24 h	r = environment.composite_rating_level([(63, 12, 0), (58, 4, 5), (51, 8, 10)])
assess_tonal_audibility	function	Tonal audibility & adjustment (ISO 1996-2 Annex C). • tone_level Lpt, masking_noise_level Lpn [dB] • centre_frequency fc [Hz]	res = environment.assess_tonal_audibility(54.1, 45.2, 430.0) • TonalAssessmentResult (.audibility, .adjustment, .plot())
tonal_audibility	function	ΔLta = Lpt−Lpn+2+lg[1+(fc/502)²·⁵] (Formula C.3). • tone_level, masking_noise_level [dB], centre_frequency [Hz]	d = environment.tonal_audibility(54.1, 45.2, 430.0) # 11.1 dB
tonal_adjustment	function	Kt(ΔLta) piecewise (Formulae C.4-C.6). • audibility ΔLta [dB]	tonal_adjustment(7.0) # 3.0 dB
tonal_adjustment_from_mean_audibility	function	Kt from mean audibility ΔL (ISO 1996-2 Table J.1). • mean_audibility [dB], coarse (Default: False)	tonal_adjustment_from_mean_audibility(5.0) # 3
critical_bandwidth	function	Critical bandwidth (ISO 1996-2 Table C.1). • centre_frequency [Hz] (100 Hz ≤ 500 Hz, else 20 %·fc)	critical_bandwidth(4000.0) # 800 Hz
tonal_seeking_survey	function	One-third-octave tonal screen (ISO 1996-2 Annex K). • levels [dB], frequencies [Hz] (15/8/5 dB neighbour rule)	flags = environment.tonal_seeking_survey(levels, freqs)
NoisePhase	dataclass	Noise phase Ti of steady emission (RD 1367/2007 Annex IV A.3.4.2 b). • hours Ti [h], laeq background-corrected LAeq,Ti [dB] • kt, kf, ki corrections [dB]; label • .correction (capped at 9 dB), .lkeq	NoisePhase(6, 50.0, kt=6, kf=3) # LKeq,Ti = 59 dB
tonal_correction	function	Kt from an unweighted 1/3-octave spectrum (Annex IV A.3.3). • levels [dB], frequencies [Hz] • Lt = Lf − Ls against the arithmetic mean of the two neighbours; 8/12, 5/8 and 3/5 dB thresholds by band range	res = environment.tonal_correction(levels, freqs) • TonalCorrectionResult (.correction, .plot())
TonalCorrectionResult	dataclass	RD 1367/2007 tonal correction. • correction Kt [dB] (0/3/6), governing_frequency • differences Lt and band_corrections per band (NaN where not evaluable) • frequencies, levels	res.correction, res.governing_frequency
low_frequency_correction	function	Kf from Lf = LCeq,Ti − LAeq,Ti (Annex IV A.3.3). • lceq, laeq [dB], background-corrected	low_frequency_correction(63.0, 50.0) # 3.0 dB
impulsive_correction	function	Ki from Li = LAIeq,Ti − LAeq,Ti (Annex IV A.3.3). • laieq, laeq [dB], background-corrected	impulsive_correction(67.0, 50.0) # 6.0 dB
total_correction	function	K = Kt + Kf + Ki, capped at 9 dB (Annex IV A.3.3). • kt, kf, ki [dB]	total_correction(6, 3, 0) # 9.0
corrected_level	function	LKeq,T = LAeq,T + Kt + Kf + Ki (Annex I A.2 c). • laeq [dB]; kt, kf, ki [dB]	corrected_level(50.0, kt=6, kf=3) # 59.0 dB
evaluation_period_level	function	LKeq,T from its noise phases (Annex IV A.3.4.2 b). • phases: NoisePhase list • hours T [h] (None = sum of Ti)	evaluation_period_level(phases, hours=12)
long_term_corrected_level	function	Annual LK,x, energy mean of the daily levels (Annex I A.2 d). • daily_levels [dB]; weights: days each level represents	long_term_corrected_level([57, 0], weights=[303, 62]) # 56.2
round_reported_level	function	Rounding of Annex IV A.3.4.2: add 0,5 dB, take the integer part. • value [dB]	round_reported_level(56.82) # 57
outdoor_quality_objectives	function	Outdoor quality objectives Ld/Le/Ln (Annex II Table A). • area_type: 'e','a','d','c','b' or an alias • urbanisation: 'existing' or 'new' (−5 dB, Article 14.2)	outdoor_quality_objectives("a") # 65/65/55 dB
indoor_quality_objectives	function	Indoor quality objectives (Annex II Table B). • building_use: 'residential','sanitary','educational' • room_type: 'living','bedrooms','classrooms','reading_rooms'	indoor_quality_objectives("residential", "bedrooms")
vibration_quality_objective	function	Indoor vibration objective Law [dB] (Annex II Table C). • building_use	vibration_quality_objective("residential") # 75.0
infrastructure_limits	function	Immission limits for new transport infrastructure (Annex III Table A1). • area_type	infrastructure_limits("a") # 60/60/50 dB
max_infrastructure_limit	function	LAmax limit for rail and airport infrastructure (Annex III Table A2). • area_type	max_infrastructure_limit("a") # 85.0 dB
activity_limits	function	Outdoor limits for activities and ports (Annex III Table B1). • area_type	activity_limits("a") # LK,d/e/n = 55/55/45 dB
adjacent_premises_limits	function	Noise transmitted to acoustically adjacent premises (Annex III Table B2). • building_use, room_type	adjacent_premises_limits("residential", "bedrooms")
RegulationLimits	dataclass	A day/evening/night limit triple of RD 1367/2007. • day, evening, night [dB]; index, reference, description • Indexable by period; .as_dict()	lim["night"]
assess_activity	function	Article 25 compliance of an activity or port. • measurements: phases keyed by period • limits: a RegulationLimits row • long_term_levels or operating_days / year_days / closed_level • new_activity (Default: True; False = Article 25.2) • period_hours	v = environment.assess_activity({"day": day}, environment.activity_limits("a"), operating_days=303) • ActivityAssessment
ActivityAssessment	dataclass	RD 1367/2007 activity verdict. • periods: PeriodAssessment tuple; limits; new_activity • .complies • .plot(); .report(path, language='es'): one-page inspection fiche → PDF	v.complies v.report("acta.pdf")
PeriodAssessment	dataclass	One evaluation period against its limit. • evaluation_period_level, reported_level (rounded) • long_term_corrected_level, reported_long_term • limit, daily_limit (+3), phase_limit (+5), max_phase_level • phase_pass, daily_pass, long_term_pass, .complies	p.reported_level, p.long_term_pass
ACOUSTIC_AREA_TYPES	constant	Acoustic area types of Article 7 of Ley 37/2003, keyed by letter. e sanitary/educational/cultural, a residential, d tertiary, c recreational, b industrial, f transport systems	ACOUSTIC_AREA_TYPES["a"]
RD1367_EVALUATION_PERIODS	constant	The three daily evaluation periods (Annex I A.1).	("day", "evening", "night")
RD1367_PERIOD_HOURS	constant	Default period durations [h] (Annex I A.1 a).	{"day": 12, "evening": 4, "night": 8}
RD1367_PERIOD_CLOCK_LIMITS	constant	Local-time start/end hour of each period (Annex I A.1 b).	{"day": (7, 19), ...}
RD1367_CORRECTION_VALUES	constant	The only values a single correction takes (Annex IV A.3.3). Each table grades its parameter 0, 3 or 6 dB	RD1367_CORRECTION_VALUES # (0.0, 3.0, 6.0)
RD1367_MAX_CORRECTION	constant	Cap on Kt + Kf + Ki [dB] (Annex IV A.3.3).	9.0
residual_sound_correction	function	Residual-noise correction L = 10 lg(10^(L'/10)−10^(Lres/10)) (Formula 16). • measured_level L', residual_level Lres [dB]	res = environment.residual_sound_correction(58.0, 50.0) • ResidualCorrectionResult (.corrected_level, .reportable_upper_bound, .reliable)
gaussian_residual_level	function	Residual Leq from percentiles (ISO 1996-2 Annex I). • l50 [dB]; exactly one of l90 / l95 (must not exceed l50)	gaussian_residual_level(50.0, l90=40.0)
combined_standard_uncertainty	function	u = √(Σ(cj·uj)²) (ISO 1996-2 Formula 2). • contributions: cj·uj products or (uj, cj) pairs	u = environment.combined_standard_uncertainty([0.59, 0.3, 2.0, 0.40, 0.38]) # 2.18
environmental_expanded_uncertainty	function	U = k·u (ISO 1996-2 §4). • standard_uncertainty [dB], confidence 0.95 (k=2) / 0.80 (k=1.3)	environment.environmental_expanded_uncertainty(2.18) # 4.36
residual_correction_uncertainty	function	Uncertainty of the residual-corrected level (Formulae F.7-F.9). • measured_level, residual_level, measured_uncertainty, residual_uncertainty [dB]	residual_correction_uncertainty(58, 50, 0.5, 2.0)
uncertainty_from_repeated_measurements	function	Energy mean & uncertainty from repeats: primary Formulae (17)+(19) route, Formula (20) approximation alongside. • levels [dB] (≥ 2); warns when they spread > 3 dB	res = environment.uncertainty_from_repeated_measurements(levels) • RepeatedMeasurementResult
TonalAssessmentResult	dataclass	Tonal assessment (ISO 1996-2). • audibility ΔLta, adjustment Kt [dB] • centre_frequency, critical_bandwidth; .plot()	res.audibility, res.adjustment
ResidualCorrectionResult	dataclass	Residual-corrected level (ISO 1996-2). • corrected_level [dB], reportable_upper_bound = measured L' [dB], margin [dB], reliable (> 3 dB; when False report the upper bound, not the correction)	res.corrected_level, res.reliable
EnvironmentalMeasurementWarning	warning class	Unreliable environmental-noise determination (ISO 1996-2:2017). • Residual within 3 dB of the measured level: no correction is allowed and only reportable_upper_bound may be reported (10.4) • Repeated levels spreading more than 3 dB: approximate_uncertainty (Formula (20)) is unreliable there (10.5 Note 2) • Subclass of PhonometryWarning	warnings.simplefilter('error', EnvironmentalMeasurementWarning) Emitted by environment.assessment.measurement
RepeatedMeasurementResult	dataclass	Repeat-measurement mean & uncertainty (ISO 1996-2). • mean_level, standard_uncertainty (Formulae (17)+(19)), approximate_uncertainty (Formula (20)) [dB], n	res.mean_level, res.standard_uncertainty
linkwitz_riley	function	Audio crossover. • x: Signal array • fs: Sample rate [Hz] • frequency: Crossover frequency [Hz] • order: Any even number (Default: 4)	lo, hi = filters.linkwitz_riley(x, fs, frequency=1000, order=4) • lo: Low-pass filtered signal • hi: High-pass filtered signal
parametric_eq	function	Parametric EQ, one shot (RBJ Audio EQ Cookbook). • x: Signal array (1D or 2D [channels, samples]) • fs: Sample rate [Hz] • sections: an EQSection or a sequence of them	y = filters.parametric_eq(x, fs, sections=filters.EQSection("peaking", 1000, gain_db=6.0))
ParametricEQ	class	Reusable parametric-EQ cascade (RBJ Audio EQ Cookbook). • fs: Sample rate [Hz] • sections: EQSection or sequence of them (cascade order) • stateful: Block processing (Default: False) • steady_ic: Steady-state initial conditions (Default: False) • .sos: the designed cascade, .filter(x), .response()	eq = filters.ParametricEQ(fs, sections) y = eq.filter(x) res = eq.response()
EQSection	dataclass	One cookbook biquad specification. • filter_type: 'peaking', 'lowshelf', 'highshelf', 'lowpass', 'highpass', 'bandpass', 'bandpass_skirt', 'notch', 'allpass' • f0: Centre/corner frequency [Hz] • gain_db: Gain (peaking/shelves) [dB] • One of q (Default: 1/√2), bw [octaves] or slope (shelves)	EQSection("peaking", 1000.0, gain_db=-6.0, bw=1.0)
EQResponseResult	dataclass	Parametric-EQ cascade response. • frequencies [Hz], magnitude_db [dB], phase_rad [rad] • section_magnitude_db: per-section magnitudes [dB] • sos: the cascade, fs, sections; .plot() magnitude + phase	res = eq.response() res.plot()
sensitivity	function	SPL Calibration. • ref_signal: Calibration signal • target_spl: Level of calibrator (Default: 94.0) • reference_pressure_pa: Reference pressure (Default: 20e-6) • frequency, calibrator_class: select the IEC 60942 Table 2 fluctuation limit the take is screened with (Default: 1000.0, '1') • narrowband: coherent Goertzel tone estimate that rejects broadband hum/noise (needs fs; Default: False)	s = sensitivity(ref_signal, target_spl=94.0) • s: Float (multiplier for pressure)
read	function	Read a measurement audio file into a Signal. • path: WAV/BWF/RF64 in the base install; FLAC, AIFF, Ogg/Opus, MP3 with [audio] • calibration_factor: digital units → Pa (Default: None; an existing sidecar is applied automatically, an explicit value wins) Native fs kept, no downmix, no normalization; int PCM scaled by 2^(bits−1); lossy sources raise LossyCompressionWarning	sig = io.read("night.wav") • sig: Signal (float64, (channels, samples), with fs, calibration, bext, labels)
info	function	Describe a file from its headers alone. • path: any supported container No sample is decoded, so a 12-hour RF64 answers instantly; compressed WAV that read refuses still describes itself	meta = io.info("night.wav") • meta: AudioFileInfo
read_blocks	function	Stream a file block by block. • path, block_size [samples] • overlap: samples shared between consecutive blocks (Default: 0) • calibration_factor: as in read; None takes the sidecar's (Default: None) Yields exactly what read returns, in slices: feeds BlockProcessing(stateful=True) unchanged	for block in io.read_blocks(p, 65536): ... • each block: a Signal with the rate, calibration, labels and provenance read gives
write	function	Write WAV/BWF (FLAC with [audio]) without touching the level. • path, x (array or Signal), fs (taken from x when x is a Signal) • subtype: 'PCM_16'/'PCM_24'/'PCM_32'/'FLOAT'/'DOUBLE' (Default: FLOAT for float data, the matching depth for integer pass-through; FLAC: PCM up to 24) • bext: None (Default) carries a Signal's own provenance; "loudness" also measures the five EBU R 128 fields in-house; a BroadcastMetadata is written as given • dither: 'tpdf' at PCM_16 only (Default: None) • rng: numpy.random.Generator or int seed for the dither noise, for byte-reproducible writes (Default: None = fresh entropy) • sidecar: write the calibration sidecar too (Default: False) Never normalizes; clipping saturates, is counted and warns (ClippingWarning); RF64 automatic past 4 GiB	io.write("out.wav", sig, subtype="PCM_24")
convert	function	Convert between lossless containers with the measurement intact. • src, dst: WAV/BWF/RF64 ↔ FLAC (lossy targets refused) Samples bit-exact at full precision, bext carried (into FLAC via the riff APPLICATION block), sidecar copied byte for byte, CodingHistory extended one line; streams, so an hour of RF64 converts flat	io.convert("night.wav", "night.flac")
Signal	dataclass	Samples plus the metadata they need. • data: (channels, samples) float64 • fs [Hz] • calibration_factor: Pa per digital unit, or None until known • channel_labels, provenance (bext), source (SignalOrigin) np.asarray(sig) yields the bare array (1D mono), so every (x, fs, ...) function accepts it; leq/laeq/ln_levels/sel/lc_peak/sound_exposure/lex_8h read fs and calibration from it directly	sig.duration, sig.n_channels sig.plot() draws the calibrated waveform
SignalOrigin	dataclass	Where a Signal came from. • path, container, format_name • bit_depth: valid bits, None for lossy codecs • lossy: the read-time warning, kept attached to the data	sig.source.lossy
AudioFileInfo	dataclass	Everything info() reads from the headers. • container, format_name, fs, channels, frames, duration, bit_depth, lossy • channel_mask / channel_labels (EXTENSIBLE speaker positions) • bext, has_ixml, cue_points	io.info(p).duration
BroadcastMetadata	dataclass	The bext chunk of EBU Tech 3285 v2, field by field. • description, originator, originator_reference, origination_date/_time • time_reference: 64-bit samples since midnight • version, umid • v2 loudness: loudness_value, loudness_range, max_true_peak_level, max_momentary_loudness, max_short_term_loudness (0x7FFF sentinel → None) • coding_history (EBU R98)	io.info(p).bext.time_reference
CuePoint	dataclass	One marker of a WAV cue chunk. • cue_id, position [samples], plus the raw chunk_id/chunk_start/block_start/sample_offset fields of the spec	io.info(p).cue_points
CalibrationSidecar	dataclass	The versioned JSON sidecar that carries the calibration. • calibration_factor, reference_spl, calibrator_frequency, calibrator_model, channel_labels, phonometry_version Lives at <audio>.phonometry.json; applied automatically by read	io.read("m.wav").calibration_factor
read_sidecar / write_sidecar / sidecar_path	function	Sidecar round-trip. • read_sidecar(path): the sidecar next to an audio file, or None (foreign or newer schema refused loudly) • write_sidecar(path, calibration_factor, ...): write one, with the optional calibrator tone metadata • sidecar_path(path): where it lives	io.write_sidecar("m.wav", cal, reference_spl=94.0)
LossyCompressionWarning	warning class	A lossy decoder produced these samples (MP3/Ogg/Opus/ADPCM): levels are not metrologically defensible. Subclass of PhonometryWarning Emitted by io.read / io.read_blocks / io.convert	warnings.simplefilter('error', io.LossyCompressionWarning)
ClippingWarning	warning class	Samples clipped while quantizing on write: count and peak overshoot in dBFS; the file is written with saturated codes rather than wrapped ones. Subclass of PhonometryWarning Emitted by io.write	warnings.simplefilter('error', io.ClippingWarning)
CatalogueRow	dataclass	The row every published catalogue hands out, with what each cell said. • name, source (document, table, PDF page and printed folio), table, variant, group, note • A quantity is None when the page had something other than a number there, and ranges, bounded_above / bounded_below, reported, unquantified, uncertainty, not_derivable and misprinted say what • basis: field or 'row' → what the source claims the value is, one of CATALOGUE_BASES; .basis_of(field) reads it, and '' means the source does not say • derived: field → how this library computed it, written by .from_printed on every row the library builds (one passed to Cls(...) is the caller's, and .printed_fields() leaves it out with its value); converted: field → the page's figure and its unit, (figure, unit), for a value held in a unit the page does not use; carried: field → the row the page gives it on, for a value it gives by reference to another row • .from_printed(**cells) builds a row and fills what follows from its cells, .printed_fields() gives the cells back; .printed(field) narrows or refuses, .why_missing(field) says what the page had, .is_derived(field), .is_approximate(field) • Checks itself when built, whoever builds it, and raises CatalogueError for a cell nothing downstream can read: a number that is NaN, a bool or a text, a hedge on a field the class does not have, a bound with no range, a value beside misprinted, a density or a length below zero, a porosity above 1; sets and mappings frozen all the way down Frozen and keyword-only; a subclass leaves out slots=True and annotates its fields float | None, int | None, bool, str, frozenset[str] or Mapping[str, ...], anything else (a bare float or int too) a TypeError	row = solids.PUBLISHED_SOLIDS['hopkins-2007-table-a2/aircrete'] row.basis_of('poisson_ratio') # 'estimated'
BandedRow	dataclass	A catalogue row that prints one value per frequency band. • One field per band, so every hedge of CatalogueRow applies to a band as to any other cell • .bands(): the bands the row prints; .spectrum(): {band_hz: value} over them, a band the page left empty left out rather than read as zero; .values_at(frequencies_hz): the row at an array of frequencies	materials.PUBLISHED_ABSORPTION['bies-2017-table-6-2/unoccupied_heavily_upholstered_seats'].spectrum()[500] # 0.81
CatalogueRow.from_printed	classmethod	A row built from the cells its page prints, completed and marked. • **cells: the printed cells under the class's field names, with their hedges, as a data file writes them • Checks every cell as the constructor does, then fills what follows from them (a modulus from a plate speed, a density and a Poisson ratio) and names each filled value in derived, never over a printed value or a hedged cell; when the printed cells a value rests on do not share one basis, the text names the basis of each • Cells the arithmetic refuses (a modulus and a shear modulus no isotropic solid has together) raise CatalogueError naming them, unless not_derivable says the value does not follow • A figure under a unit the class takes as an alias of its own (absorption_area_125_ft2 on AbsorptionAreaSpectrum) is converted on its digits with an exact factor, rounded once, and recorded in converted • The one path that works anything out, and every packaged catalogue is built through it; Cls(...) stays literal. A derived among the cells raises CatalogueError	row = solids.SolidMaterial.from_printed(name='Board', source='...', density_kg_m3=860.0, plate_longitudinal_speed_m_s=1490.0, poisson_ratio=0.3) row.is_derived('youngs_modulus_pa') # True
CatalogueRow.printed_fields	method	The cells the page prints, as from_printed takes them. • Every field, hedges, converted and carried included, without the derived values, without derived, and without a field left at a default that holds nothing; an empty per stays, since its default is a person • type(row).from_printed(**row.printed_fields()) is the row again for every row .from_printed builds. Change a cell here and build again to edit a row: dataclasses.replace keeps derived values that no longer follow from the cell that changed	cells = row.printed_fields() cells['density_kg_m3'] = 2400.0 row = type(row).from_printed(**cells)
BandedRow.values_at	method	The row at an array of frequencies, one band per frequency. • frequencies_hz: band centres [Hz], any shape; each matches the band whose centre is nearest on a logarithmic scale, within a sixth of the band spacing, so a nominal, an exact base-ten and an exact base-two centre read the same band • A band the row does not print raises ValueError with what the page had there, never a zero; a frequency between bands raises naming the nearest • For a function that takes one value per band by position: the surfaces of room.sabine_reverberation_time, or noise_control.enclosure_insertion_loss given row.values_at as its transmission loss	seats.values_at([125.0, 250.0, 500.0]) • a new float64 array of the frequencies' shape
CatalogueError	exception	A catalogue that does not say what a reader needs to trust it. A table without its citation or its rows, two rows under one key, a NaN or a name written twice in its JSON, a / in a row key; a row that breaks the contract it is checked against when built, from a file or by hand. Subclass of ValueError	except io.CatalogueError: ...
CATALOGUE_BASES	constant	What a source can claim a value is. 'measured', 'declared', 'calculated', 'estimated' and 'extended'; no entry means the source does not say	'estimated' in io.CATALOGUE_BASES # True
verify_filter_class	function	IEC 61260 class check of a bank design. For '2014' it grades Table 1 (5.10), the effective bandwidth deviation (5.12) and the summation of output signals (5.16), the last two as IEC 61260-2:2016 tests them (Formulas (1) to (3)); '1995' grades its Table 1 alone. • bank: an OctaveFilterBank • keyword-only: num_points, frequency grid points per band (Default: 32768) • keyword-only: edition, '2014' (classes 1/2, default) or '1995' (IEC 61260:1995 / ANSI S1.11-2004, adds class 0) • keyword-only: points_per_bandwidth, S of IEC 61260-2 Formula (1), at least 24 (Default: 24)	result = filters.verify_filter_class(bank) result.requirement_class("summation") • FilterComplianceResult
FilterComplianceResult	dataclass	IEC 61260 filter class-compliance result. • overall_class: strictest class every band meets on every requirement graded: 1/2 ('2014'), 0/1/2 ('1995'), or None • bands: per-band verdict dictionaries, with bandwidth_deviation_db and summation_min_db / summation_max_db for '2014' • requirements, .requirement_class(name), .binding_margin_db(name, cls): each requirement on its own • range_limited: stop-band mask beyond the processing Nyquist not exercised • .available_classes() / .reference_class(): the edition's classes and the fiche's reference class • .plot(requirement=...): the relative attenuation over its corridor (default), 'effective_bandwidth' or 'summation' • .report(path, *, metadata=None, required_class via metadata): one-page PDF fiche	verify_filter_class(bank).report("iec61260.pdf")
verify_time_invariance	function	Time-invariant operation of a bank, IEC 61260-1:2014 5.14 (IEC 61260-2:2016 7.4). An exponential sweep through the bank itself, decimation included, against Formula (17), ±0.4 dB (class 1) or ±0.6 dB (class 2). • bank: an OctaveFilterBank • keyword-only: seconds_per_decade, the sweep rates, each 2 s to 5 s (Default: (2.0, 5.0))	res = filters.verify_time_invariance(bank) • TimeInvarianceResult
TimeInvarianceResult	dataclass	The swept verdict of a bank. • output_levels_db / expected_levels_db: (rates, bands), re the sweep level; deviations_db • band_classes, overall_class, worst_deviation_db • seconds_per_decade, start_frequency_hz, end_frequency_hz, sweep_durations_s, averaging_times_s • no truth value; .plot() draws each band's deviation per rate	res.overall_class
swept_band_level	function	IEC 61260-1:2014 Formula (17): the time-averaged output of an exponential sweep. • input_level_db • keyword-only: fraction, sweep_duration_s, averaging_time_s, start_frequency_hz, end_frequency_hz, reference_attenuation_db (Default: 0)	filters.swept_band_level(127.0, fraction=3, sweep_duration_s=30, averaging_time_s=30, start_frequency_hz=0.01, end_frequency_hz=1e6) • 107.969... (IEC 61260-2 and -3 Annex B, 107,97 dB)
swept_level_uncertainty	function	The standard uncertainty of Formula (17) from the sweep, Annex A of IEC 61260-2 and -3. Formula (A.2) with the square its printed form drops (see the errata registry) • keyword-only: input_level_uncertainty_db, sweep_duration_s, sweep_duration_uncertainty_s, averaging_time_s, averaging_time_uncertainty_s, start_frequency_hz, start_frequency_uncertainty_hz, end_frequency_hz, end_frequency_uncertainty_hz, display_resolution_db (Default: 0)	u = filters.swept_level_uncertainty(...) • u [dB], standard; 2 * u the expanded (0.115 dB in A.3.5)
periodic_test_frequencies	function	The 15 test frequencies of IEC 61260-3:2016 Clause 13, Formulas (1) and (2), k = -7 .. 7, any bandwidth designator • fraction: b (1, 3, ...)	omega = filters.periodic_test_frequencies(3) • read-only array of Ω_k; omega[8] # 1.02667 (Table C.1)
PERIODIC_TEST_ATTENUATION_LIMITS_DB	mapping	IEC 61260-3:2016 Table 1: class → the minimum and maximum relative attenuation [dB] for |k| = 0 .. 7, the stop-band maximum inf	filters.PERIODIC_TEST_ATTENUATION_LIMITS_DB[1][7] # (70.0, inf)
verify_filter_periodic	function	The periodic tests of IEC 61260-3:2016 on a laboratory's results. Each clause (10.2 or 10.3, 11.7, 11.9, 13) judged by metrology.verify_conformance with the maxima of IEC 61260-1:2014 Annex B; results 5.3 makes unusable are named • filter_class: 1 or 2 • measurements: a FilterPeriodicMeasurements • keyword-only: fraction, b of the filters of Clause 13 • keyword-only: pattern_approval_public, whether the model's IEC 61260-2 approval is public (Default: False)	res = filters.verify_filter_periodic(1, record, fraction=3) • FilterPeriodicVerification
FilterPeriodicMeasurements	dataclass	What a laboratory measured in the periodic tests, each result with its expanded uncertainty: midband_attenuations_db (10.2), bandwidth_deviations_db (10.3), linearity_deviations_db with linearity_levels_below_upper_db (11.7), range_linearity_deviations_db (11.9), relative_attenuations_db rows of 15 with NaN where 13.4 drops a frequency (13), and optional set_midband_frequencies_hz / tested_midband_frequencies_hz / linearity_midband_frequencies_hz labels, which let the verdict check the three filters of 11.3 and the frequencies of 13.4	filters.FilterPeriodicMeasurements(midband_attenuations_db=[0.1], midband_uncertainties_db=[0.15])
PeriodicTestClause	dataclass	The verdict on one clause of IEC 61260-3. • clause, title, labels, verifications (one ConformanceVerification per result) • passes, failed, unusable (5.3) • no truth value; .plot() as Figure C.1, clause 13 as margins against Ω_k	res.clause("13").failed
FilterPeriodicVerification	dataclass	The IEC 61260-3:2016 verdict. • filter_class, fraction, pattern_approval_public, measurements, clauses; clause(id) • passes: every clause a complete test grades was measured on the filters and frequencies it requires and every result conforms • missing, incomplete (11.3, 13.1, 13.4), coverage_checked, failed, unusable • statement: the text of Clause 14 k), l) or m), with the caveat of 1.5 when the pattern approval is not public • no truth value; .plot() draws every result's margin, clause by clause	res.passes, res.statement
class_limits	function	IEC 61260 Table 1 acceptance limits. • fraction: bandwidth designator denominator b (1, 3, ...) • filter_class: 1 or 2 ('2014'); 0, 1 or 2 ('1995') • omega: normalized frequencies f/fm • edition: '2014' (default) or '1995'	lo, hi = filters.class_limits(3, 0, omega, edition="1995") • lo / hi: min/max relative attenuation [dB] (hi is inf outside the pass-band)
verify_weighting_class	function	Weighting tolerance check against IEC 61672-1:2013 Table 3 (A/C/Z), ANSI S1.4-1983 Tables IV/V (B, Types as classes) or IEC 61012:1990 Table 1 (AU), at the exact base-10 frequencies, plus the 5.5.7 between-nominals sweep. edition="1979" grades against IEC 651:1979 Table V instead, which publishes the laboratory-grade Type 0 (A, B and C). • wf: a WeightingFilter (A, B, C, AU or Z) • keyword-only: sweep_points (Default: 4096) • keyword-only: edition (Default: "2013"; "1979" for Types 0-3)	result = filters.verify_weighting_class(wf) • WeightingComplianceResult
WeightingComplianceResult	dataclass	Weighting class verdict of a WeightingFilter. • overall_class: 1, 2 or None (0-3 or None for '1979') • bands: per-frequency class, deviation and margin_class<c>_db [dB] • between_nominals: the 5.5.7 sweep, or None when no row was in range • curve, edition, fs [Hz], sweep_points • range_limited: finite-lower-limit rows beyond Nyquist	result.overall_class, result.range_limited
weighting_class_limits	function	IEC 61672-1:2013 Table 3 acceptance limits, or the IEC 651:1979 Table V ones with edition="1979". • weighting_class: 1 or 2 (0-3 for "1979", where class N is instrument Type N) • edition (Default: "2013")	f, lo, hi = filters.weighting_class_limits(1) • f: 34 nominal frequencies [Hz] • lo / hi: lower/upper deviation limits [dB] (lo is -inf where one-sided)
nominal_frequencies	function	ANSI Frequency generator. • fraction: 1, 3, etc. (Required) • limits: [f_min, f_max] (Default: [12, 20000])	f_cen, f_low, f_high, labels = filters.nominal_frequencies(fraction=3) • f_cen: List of center frequencies [Hz] • f_low: List of lower edges [Hz] • f_high: List of upper edges [Hz] • labels: IEC nominal frequency labels
normalized_frequencies	function	Standard IEC Frequencies. • fraction: 1 or 3	freqs = filters.normalized_frequencies(fraction=3) • freqs: List of standard center frequencies [Hz]
sweep_signal	function	ESS excitation (ISO 18233 Annex B). • fs: Sample rate [Hz] • f1: Start frequency [Hz] • f2: Stop frequency [Hz] (≤ fs/2) • seconds: Duration [s] • amplitude: Peak (Default: 1.0) • fade: Half-Hann fraction (Default: 0.01)	s = room.sweep_signal(48000, 20, 20000, 3.0) • 1D exponential sine sweep
inverse_filter	function	Farina inverse filter for an ESS. • Same parameters as sweep_signal	inv = room.inverse_filter(48000, 20, 20000, 3.0) • Time-reversed, +6 dB/oct compensated sweep
impulse_response	function	Sweep deconvolution (ISO 18233 B.5). • recorded: Recorded response (1D) • reference: Emitted sweep (1D) • fs: Sample rate [Hz] • method: 'spectral' (Default) or 'farina' • f_range: (f1, f2) for 'farina' • regularization: Tikhonov term (Default: 1e-6) • length: causal samples (Default: len(recorded)) • return_full: keep distortion tail (Default: False)	ir = room.impulse_response(rec, sweep, fs) • ImpulseResponseResult (array-like; .plot())
mls_signal	function	Maximum-length sequence (ISO 18233 Annex A). • order: Register length N, 2-20	mls = room.mls_signal(16) • Bipolar sequence, length 2**N − 1
mls_impulse_response	function	IR from a periodic MLS. • recorded: Response spanning whole MLS periods (1D) • mls: Excitation sequence • length: IR samples (Default: 2**N − 1) • fs: optional sample rate for the plot time axis	ir = room.mls_impulse_response(rec, mls) • ImpulseResponseResult (array-like; .plot())
ImpulseResponseResult	dataclass	Recovered impulse response with metadata. • ir: IR samples • fs [Hz] or None (e.g. an MLS recovery without one) • method: 'spectral'/'farina'/'mls'/'golay' • array-like: np.asarray(res), indexing, len() and shape/dtype forward to ir • .plot()	ir = room.impulse_response(rec, sweep, fs) room_parameters(ir, fs) # drop-in array
golay_pair	function	Complementary Golay pair (Havelock Pt. I Ch. 6). • order: recursion steps n, 1-22; each code has 2**n samples Periodic autocorrelations sum to an exact 2L·delta	a, b = room.golay_pair(14) • Two bipolar codes, length 2**n
golay_impulse_response	function	IR from a periodic Golay-pair excitation. • recorded_a / recorded_b: steady-state responses to each code (whole periods) • pair: the (a, b) codes • length: IR samples (Default: 2**n) • fs: optional sample rate for the plot time axis Noiseless LTI recovery is exact (machine precision)	ir = room.golay_impulse_response(rec_a, rec_b, pair) • ImpulseResponseResult (array-like; .plot())
shaped_sweep_signal	function	Sweep with an arbitrary target spectrum (Mueller & Massarani Secs. 4.2-4.3). • fs, f1, f2, seconds • target: 'pink' (Default), 'white' or (frequencies_hz, magnitude_db) • amplitude (Default: 1.0), start_delay (Default: 0.05·seconds), fade (Default: 0.01) Group delay grows with the target power: near-constant envelope	sweep = room.shaped_sweep_signal(fs, 50, 5000, 2, target="pink") • ShapedSweepResult (array-like; .plot())
ShapedSweepResult	dataclass	Synthesized shaped sweep. • signal, fs, frequencies, magnitude (imposed, peak 1), group_delay [s], f_range, crest_factor_db • array-like: usable directly as the deconvolution reference • .plot(): waveform + Welch spectrum vs target	ir = room.impulse_response(rec, np.asarray(sweep), fs)
ImpulseResponseWarning	warning class	Suspect recovered impulse response. Emitted e.g. for MLS aliasing in the recovery	warnings.simplefilter('error', ImpulseResponseWarning)
plot_excitation	function	Plot an excitation signal. • signal: sweep or MLS samples (1D) • fs: Sample rate [Hz] • kind: 'sweep' (default) or 'mls'	plot_excitation(sweep, fs, kind="sweep") • waveform + spectrogram / spectrum axes
decay_curve	function	Schroeder decay curve (ISO 3382-1 5.3.3). • ir: Impulse response (1D) • fs: Sample rate [Hz] • band: Band centre [Hz] (Default: None → broadband) • fraction: 1 or 3 (Default: 1) • zero_phase: forward-backward band filtering, halves the 125 Hz short-T bias (Default: False)	dc = room.decay_curve(ir, fs) → DecayCurve times, levels = dc still unpacks (times [s], levels [dB], 0 dB at t=0) dc.plot() draws the decay + EDT/T20/T30 fits
DecayCurve	dataclass	Schroeder decay curve (ISO 3382-1 5.3.3). • times: from the direct sound [s] • levels: decay [dB], 0 dB at t = 0, up to the noise truncation point • band: centre [Hz] or None (broadband) • iterable: unpacks as times, levels • .plot(): decay + EDT/T20/T30 fits	dc = room.decay_curve(ir, fs) dc.times, dc.levels, dc.band
room_parameters	function	Room acoustics (ISO 3382-1/2). • ir: Impulse response (1D) • fs: Sample rate [Hz] • limits: (f_min, f_max) or None (Default: (125, 4000)) • fraction: 1 or 3 (Default: 1) • zero_phase: forward-backward octave filtering, halves the 125 Hz short-T T30 bias (Default: False)	res = room.room_parameters(ir, fs) • RoomAcousticsResult per band
RoomAcousticsResult	dataclass	Per-band room parameters. • frequencies [Hz] • edt, t20, t30 [s] • c50, c80 [dB], d50, ts [s] • dynamic_range [dB] • edt_valid/t20_valid/t30_valid • curvature [%]	res.t30, res.c80, res.t30_valid • Arrays with one entry per band
sound_strength	function	Sound strength G (ISO 3382-1 A.2.1, Eq. (A.1)). • ir: hall impulse response (1D) • reference_ir: same source at 10 m in a free field (1D) • fs: Sample rate [Hz] • reference_level: L_pE,10 [dB] instead of reference_ir (exactly one of the two) • limits: (f_min, f_max) or None (Default: (125, 4000)) • fraction: 1 or 3 (Default: 1)	res = room.sound_strength(ir, ref, fs) • SoundStrengthResult per band
SoundStrengthResult	dataclass	Per-band sound strength. • frequencies [Hz] or None • strength: G [dB] • exposure_level: L_pE [dB] • reference_level: L_pE,10 [dB] • .plot(): G against the Table A.1 typical range	res.strength, res.exposure_level • strength == exposure_level - reference_level
sound_pressure_exposure_level	function	L_pE of an impulse response (ISO 3382-1 Eq. (A.2)). • ir: Impulse response (1D) • fs: Sample rate [Hz] • limits: (f_min, f_max) or None (Default: (125, 4000)) • fraction: 1 or 3 (Default: 1)	lpe = room.sound_pressure_exposure_level(ir, fs) • [dB] re 20 uPa, one per band
free_field_reference_level	function	Refer a free-field level to 10 m (ISO 3382-1 Eqs. (A.4)/(A.8)). • level: measured level [dB] • distance: of that measurement [m], printed for >= 3 m	room.free_field_reference_level(75.03, 5.0) • 69.0094 dB
reverberation_room_reference_level	function	Free-field reference from a diffuse-field reading (ISO 3382-1 Eq. (A.5)). • reverberation_room_level: spatial-average L_pE in that room [dB] • absorption_area: A [m2]	room.reverberation_room_reference_level(80.0, 10.0) • 53.0 dB
sound_strength_from_power	function	G from the source's power level (ISO 3382-1 Eq. (A.9)). • pressure_level: L_p in the room [dB] • power_level: L_W of the source [dB]	room.sound_strength_from_power(80.0, 100.0) • 11.0 dB
directivity_energy_average	function	Energy mean over bearings round the source (ISO 3382-1, note to Eq. (A.4)). • levels: one per bearing [dB], evenly spaced over a full turn, at least 29	room.directivity_energy_average(levels) • [dB]; raises below 29 bearings
early_lateral_energy_fraction	function	Early lateral energy fraction (ISO 3382-1 Eqs. (A.14)/(A.15)). • ir: omnidirectional response at the point (1D), which also sets t = 0 • lateral_ir: figure-of-eight response at the same point (1D) • fs: Sample rate [Hz] • weighting: 'squared' (J_LF) or 'cosine' (J_LFC) • limits: (f_min, f_max) or None (Default: (125, 4000)) • fraction: 1 or 3 (Default: 1)	res = room.early_lateral_energy_fraction(omni, fig8, fs) • LateralEnergyResult per band
LateralEnergyResult	dataclass	Per-band lateral energy fraction. • frequencies [Hz] or None • energy_fraction: J_LF or J_LFC, dimensionless • weighting: which of the two was computed • .plot(): against the Table A.1 range	res.energy_fraction, res.weighting
LATERAL_WEIGHTINGS	constant	('squared', 'cosine'), the two angular weightings Eqs. (A.14) and (A.15) print.	room.LATERAL_WEIGHTINGS
EARLY_LATERAL_WINDOW_S	constant	(0.005, 0.080) s, the numerator window of Eqs. (A.14)/(A.15) from the direct sound.	room.EARLY_LATERAL_WINDOW_S
EARLY_ENERGY_LIMIT_S	constant	0.080 s, the upper limit of their denominator.	room.EARLY_ENERGY_LIMIT_S
late_lateral_sound_level	function	Late lateral sound level (ISO 3382-1 Eq. (A.16)). • ir: omnidirectional response at the point (1D), for t = 0 • lateral_ir: figure-of-eight response at the same point (1D) • reference_ir: same source at 10 m in a free field (1D) • fs: Sample rate [Hz] • reference_level: L_pE,10 [dB] instead of reference_ir • limits, fraction: as above	res = room.late_lateral_sound_level(omni, fig8, ref, fs) • LateLateralResult per band
LateLateralResult	dataclass	Per-band late lateral level. • frequencies [Hz] or None • levels: L_J [dB] • reference_level: L_pE,10 [dB] • .plot(): against the Table A.1 range, with the Eq. (A.17) average	res.levels, res.reference_level
late_lateral_average	function	Energy average of L_J over four octave bands (ISO 3382-1 Eq. (A.17)). • levels: the 125 Hz, 250 Hz, 500 Hz and 1 kHz values [dB], exactly four	room.late_lateral_average([-8.0] * 4) • -8.0 dB; four equal values are unchanged
LATE_LATERAL_START_S	constant	0.080 s, where the numerator of Eq. (A.16) starts.	room.LATE_LATERAL_START_S
LATE_LATERAL_AVERAGE_BANDS_HZ	constant	(125, 250, 500, 1000) Hz, the four bands Eq. (A.17) averages.	room.LATE_LATERAL_AVERAGE_BANDS_HZ
interaural_cross_correlation	function	Interaural cross correlation (ISO 3382-1 Eqs. (B.1)/(B.2)). • left, right: ear-canal responses (1D, same length) • fs: Sample rate [Hz] • window: (t1, t2) [s] from the direct sound, t2 None for the end (Default: (0.0, None)) • limits, fraction: as above	res = room.interaural_cross_correlation(left, right, fs) • InterauralCorrelationResult per band
InterauralCorrelationResult	dataclass	Per-band interaural correlation. • frequencies [Hz] or None • coefficient: IACC • delay: lag of the maximum [s], positive when the right ear lags • lag [s] and correlation: the function itself, one row per band • .plot(): the function over the search window	res.coefficient, res.delay
IACC_SEARCH_S	constant	0.001 s, the half-width of the Eq. (B.2) search window.	room.IACC_SEARCH_S
IACC_EARLY_WINDOW_S	constant	(0.0, 0.080) s, the early window of B.4.	room.IACC_EARLY_WINDOW_S
IACC_LATE_START_S	constant	0.080 s, where B.4's reverberant window starts.	room.IACC_LATE_START_S
IACC_JND	constant	0.075, the just-noticeable difference B.4 assumes for IACC.	room.IACC_JND
stage_support	function	Early and late stage support (ISO 3382-1 Eqs. (C.1)/(C.2)). • ir: platform response 1,0 m from the source (1D) • fs: Sample rate [Hz] • limits: (f_min, f_max) or None (Default: (250, 2000), the bands C.2.4 averages) • fraction: 1 or 3 (Default: 1)	res = room.stage_support(ir, fs) • StageSupportResult per band
StageSupportResult	dataclass	Per-band stage support. • frequencies [Hz] or None • early: ST_Early [dB] • late: ST_Late [dB] • .plot(): both against the Table C.1 ranges	res.early, res.late
STAGE_DIRECT_WINDOW_S	constant	(0.0, 0.010) s, the direct-sound window both equations divide by.	room.STAGE_DIRECT_WINDOW_S
EARLY_SUPPORT_WINDOW_S	constant	(0.020, 0.100) s, the numerator of Eq. (C.1); it starts at 20 ms, not at 10 ms.	room.EARLY_SUPPORT_WINDOW_S
LATE_SUPPORT_WINDOW_S	constant	(0.100, 1.000) s, the numerator of Eq. (C.2); it stops at one second.	room.LATE_SUPPORT_WINDOW_S
STAGE_SUPPORT_DISTANCE_M	constant	1.0 m between source and microphone (C.2.1).	room.STAGE_SUPPORT_DISTANCE_M
STAGE_SUPPORT_HEIGHTS_M	constant	(1.0, 1.5) m, the two heights C.2.3 permits for both.	room.STAGE_SUPPORT_HEIGHTS_M
STAGE_SUPPORT_BANDS_HZ	constant	(250, 500, 1000, 2000) Hz, the bands C.2.4 averages.	room.STAGE_SUPPORT_BANDS_HZ
STAGE_SUPPORT_POSITIONS	constant	3 positions C.2.3 asks for and C.2.4 averages over.	room.STAGE_SUPPORT_POSITIONS
STAGE_SUPPORT_STANDARD_DEVIATION_DB	constant	1.0 dB for one band in one position (C.2.4).	room.STAGE_SUPPORT_STANDARD_DEVIATION_DB
STAGE_SUPPORT_SINGLE_NUMBER_STANDARD_DEVIATION_DB	constant	0.3 dB for the single number (C.2.4); it is 1 dB over the root of the twelve readings.	room.STAGE_SUPPORT_SINGLE_NUMBER_STANDARD_DEVIATION_DB
reverberation_time_standard_deviation	function	Standard deviation of a measured T (ISO 3382-1 Eqs. (4)/(5)). • reverberation_time [s] • bandwidth [Hz], from filter_bandwidth • evaluation_range: 20 or 30 [dB] (Default: 30) • decays: n per position (Default: 10, what 7.2 values an integrated response at) • positions: N source-receiver combinations (Default: 1)	room.reverberation_time_standard_deviation(2.0, 710.0, positions=12) • 0.009044 s
filter_bandwidth	function	Bandwidth of a fractional-octave filter (ISO 3382-1 7.1). • centre: mid-band frequency [Hz] • fraction: 1 or 3 (Default: 1)	room.filter_bandwidth(1000.0) → 710.0 Hz
minimum_reliable_reverberation_time	function	Shortest decay a forward analysis can resolve (ISO 3382-1 Eqs. (6)/(7)). • bandwidth [Hz] • detector_time: T of the averaging detector [s] (Default: 0.0, no detector)	room.minimum_reliable_reverberation_time(88.75) • 0.1803 s
FILTER_BANDWIDTH_FRACTION	constant	{1: 0.71, 3: 0.23}, the two bandwidths 7.1 prints as a fraction of the centre.	room.FILTER_BANDWIDTH_FRACTION[1] → 0.71
DECAY_UNCERTAINTY_COEFFICIENTS	constant	{20.0: (0.88, 1.90), 30.0: (0.55, 1.52)}, the printed pairs of Eqs. (4) and (5).	room.DECAY_UNCERTAINTY_COEFFICIENTS[30.0]
INTEGRATED_RESPONSE_DECAYS	constant	10, the decays per position 7.2 values an integrated impulse response at.	room.INTEGRATED_RESPONSE_DECAYS
MINIMUM_BANDWIDTH_TIME_PRODUCT	constant	16.0, the B·T of Eq. (6).	room.MINIMUM_BANDWIDTH_TIME_PRODUCT
MINIMUM_DETECTOR_MULTIPLE	constant	2.0, the multiple of the detector's own T in Eq. (7).	room.MINIMUM_DETECTOR_MULTIPLE
TABLE_A1	constant	ISO 3382-1 Table A.1, keyed by the symbol the standard prints: G, EDT, C80, D50, Ts, J_LF, L_J. • each value is an AuditoriumQuantity	room.TABLE_A1['G'].averaging_bands_hz → (500.0, 1000.0)
AuditoriumQuantity	dataclass	One row of Table A.1. • symbol, aspect, unit • averaging_bands_hz: the bands its single number averages, two or four • just_noticeable_difference: None for L_J, whose JND the table prints as 'Not known' • relative_jnd: True only for EDT's 'Rel. 5 %' • typical_range, energy_averaged	room.TABLE_A1['L_J'].energy_averaged → True
single_number_average	function	The Table A.1 single number of one quantity (A.5). • symbol: as TABLE_A1 keys it • values: per-band values • frequency: the band centres [Hz]	room.single_number_average('G', g, freqs) • arithmetic, except L_J, which goes through Eq. (A.17)
octave_pair_averages	function	The low, mid and high pair averages of A.5. • values: per-band values • frequency: the band centres [Hz], all six octaves	room.octave_pair_averages(v, freqs) • {'low': ..., 'mid': ..., 'high': ...}
perceptibly_different	function	Whether two values differ by the Table A.1 JND. • symbol, first, second • relative for EDT, absolute otherwise; raises for L_J	room.perceptibly_different('EDT', 0.5, 0.56) → True
minimum_receiver_positions	function	Fewest microphone positions a hall wants (Table A.2). • seats: the number of seats	room.minimum_receiver_positions(1000) → 8.0 • clamped to the 6 to 10 A.4 authorises
gliding_directivity_deviation	function	Deviation of each gliding 30 degree arc from the whole turn (4.2.1). • levels: one per bearing [dB], evenly spaced over a full turn	room.gliding_directivity_deviation(levels) • one deviation per bearing [dB]
source_directivity_limit	function	The Table 1 limit for one octave band. • centre: nominal band centre [Hz], one of the six the table prints	room.source_directivity_limit(4000.0) → 6.0 dB
MAX_SOURCE_DIRECTIVITY_DEVIATION_DB	constant	Table 1, six octave bands to their maximum deviation in dB: 1, 1, 1, 3, 5, 6.	room.MAX_SOURCE_DIRECTIVITY_DEVIATION_DB[1000.0] → 3.0
DIRECTIVITY_ARC_DEG	constant	30.0 degrees, the arc each gliding average of 4.2.1 covers.	room.DIRECTIVITY_ARC_DEG
DIRECTIVITY_STEP_DEG	constant	5.0 degrees, the step 4.2.1 asks for without a turntable; it divides a turn into 72.	room.DIRECTIVITY_STEP_DEG
DIRECTIVITY_SURVEY_DISTANCE_M	constant	1.5 m, the shortest source-to-microphone distance 4.2.1 allows in a survey.	room.DIRECTIVITY_SURVEY_DISTANCE_M
OCTAVE_PAIRS_HZ	constant	The three A.5 pairs: low 125+250, mid 500+1000, high 2000+4000 Hz.	room.OCTAVE_PAIRS_HZ['mid']
MID_FREQUENCY_OCTAVES_HZ	constant	(500, 1000) Hz, the octave route of Clause 9.1 to T30,mid.	room.MID_FREQUENCY_OCTAVES_HZ
MID_FREQUENCY_THIRD_OCTAVES_HZ	constant	(400, 500, 630, 800, 1000, 1250) Hz, the other route Clause 9.1 prints, and the one a one-third-octave analysis takes.	room.MID_FREQUENCY_THIRD_OCTAVES_HZ
TEST_REPORT_ITEMS	constant	The fifteen items Clause 9.2 says a test report shall include, a) to o), in order. Clause 9 is normative.	len(room.TEST_REPORT_ITEMS) → 15
AuditoriumWarning	warning class	A measurement outside the conditions ISO 3382-1 prints for it. • emitted for a room response cut short of the 30 dB of A.2.1 • for a response of either kind that ends before its lowest band's filter has rung down • and for a free-field distance under 3 m	warnings.simplefilter('error', room.AuditoriumWarning)
REFERENCE_DISTANCE_M	constant	10.0 m, the free-field distance G is referenced to (ISO 3382-1 A.2.1).	room.REFERENCE_DISTANCE_M → 10.0
MINIMUM_REFERENCE_DISTANCE_M	constant	3.0 m, the shortest distance Eqs. (A.4)/(A.8) are printed for.	room.MINIMUM_REFERENCE_DISTANCE_M → 3.0
MAXIMUM_DIRECTIVITY_STEP_DEG	constant	12.5 deg, the coarsest bearing step the note to Eq. (A.4) allows.	room.MAXIMUM_DIRECTIVITY_STEP_DEG → 12.5
SOUND_STRENGTH_POWER_OFFSET_DB	constant	31.0 dB, the printed offset of Eq. (A.9); 10 lg(4 pi $10^{2}$) = 30.9921 dB rounded.	room.SOUND_STRENGTH_POWER_OFFSET_DB → 31.0
DIFFUSE_FIELD_REFERENCE_OFFSET_DB	constant	37.0 dB, the printed offset of Eq. (A.5); 10 lg(16 pi $10^{2}$) = 37.0127 dB rounded.	room.DIFFUSE_FIELD_REFERENCE_OFFSET_DB → 37.0
open_plan_metrics	function	Open-plan office metrics (ISO 3382-3). • positions_m: Source distances [m] (≥ 4) • spl_a_speech: A-weighted speech level per position [dB] • sti_values: STI per position	m = room.open_plan_metrics(r, lp, sti) • OpenPlanResult
plot_open_plan_geometry	function	Open-plan measurement line to scale. • positions [m] (1-D) • rd, rp [m] (markers) • language	plot_open_plan_geometry([2, 4, 6, 8, 12, 16], rd=6.5, rp=13.0) • Also OpenPlanResult.plot_geometry()
OpenPlanResult	dataclass	Open-plan single numbers. • d2s: Spatial decay rate [dB/doubling] • lp_as_4m: Speech level at 4 m [dB] • rd: Distraction distance [m] • rp: Privacy distance [m]	m.d2s, m.rd, m.rp • nan when undefined
image_source_rir	function	Image-source room impulse response (Kuttruff 4.1 / Vorländer 11). • dimensions: (Lx, Ly, Lz) [m] • source/receiver: (x, y, z) [m] • absorption: scalar / (6,) per-wall / per-band / (6, n) [0, 1] • fs [Hz], max_order (Default: 20) • air_attenuation: intensity m [1/m] • frequencies [Hz] for a per-band RIR	res = room.image_source_rir((7,5,3), (2,1.6,1.5), (5.2,3.4,1.7), 0.12, fs=48000) • ImageSourceResult
ImageSourceResult	dataclass	Synthetic RIR by image sources. • ir: sampled RIR (1D or per-band) • exact reflection table times/distances/orders/amplitudes/image_positions • direct_time [s] • .plot(), .plot_geometry() (room plan with the image lattice): reflectogram	res.ir, res.times, res.orders res.plot()
audible_image_count / reflection_density	function	Shoebox image count (Kuttruff Eq. 9.23) and reflection density (Eq. 4.6). • audible_image_count(order): (2/3)(2i³+3i²+4i) • reflection_density(t, volume, speed_of_sound=343): 4πc³t²/V	audible_image_count(10) # 1560 reflection_density(0.1, 120.0)
steady_state_field	function	Steady-state room field (Bies 6.4). • sound_power_level Lw [dB] • surface_area S [m²], mean_absorption ᾱ (0, 1) • distances [m] (Default: 0.1–10 rc) • directivity Q (Default: 1) • characteristic_impedance [Pa·s/m] for the ρc term	f = room.steady_state_field(90.0, 100.0, 0.2) • SteadyFieldResult
SteadyFieldResult	dataclass	SPL vs distance, direct/reverberant/total. • distances [m] • direct/reverberant/total [dB] • critical_distance [m], room_constant [m²] • .plot()	f.total, f.critical_distance f.plot()
room_constant / sabine_absorption_area / critical_distance / schroeder_frequency / steady_state_spl / SOURCE_POWER_MODELS	function / mapping	Steady-field building blocks (Bies 6.43/6.44, Kuttruff 3.44/5.44, VDI 2081-1 Eq. 36/37). • room_constant(S, ᾱ) = Sᾱ/(1-ᾱ) [m²] • sabine_absorption_area(V, T, speed_of_sound=343) = 24 ln10/c₀ · V/T [m²] • critical_distance(R | absorption_area=A, directivity=1) = √(QR/16π), or √(QA/16π) from the absorption area [m] • schroeder_frequency(T, V) = 2000√(T/V) [Hz] • steady_state_spl(Lw, r, R | absorption_area=A, directivity=1, source_model='constant_power') = Lw + 10 lg(Q/4πr² + 4/R), with 4/A in place of 4/R from the absorption area [dB]; r=None gives the reverberant field alone; exactly one absorption measure, directivity scalar or per band • SOURCE_POWER_MODELS: 'constant_power' / 'constant_volume' (Π₀Q, conservative) / 'constant_pressure' (Π₀/Q), Norton Table 4.5	R = room.room_constant(100, 0.2) critical_distance(R) steady_state_spl(90, None, R)
room_modes	function	Normal modes of a rectangular room (Long, Architectural Acoustics 2e, Eq. 8.43). • dimensions: (lx, ly, lz) [m] • max_frequency [Hz] (Default: 200) • speed_of_sound [m/s] (Default: 343) • reverberation_time [s] (optional, adds the Schroeder frequency)	m = room.room_modes((7, 5, 3), max_frequency=100.0) • RoomModesResult
RoomModesResult	dataclass	Sorted mode list of a shoebox. • orders: (N, 3) (nx, ny, nz) • frequencies [Hz], ascending • kinds: 'axial'/'tangential'/'oblique' • volume, surface_area, edge_length, schroeder_frequency • count_by_kind(), density(f) • .plot(): mode ladder by family + modal density	m.frequencies[0], m.count_by_kind() m.plot()
room_mode_frequency / room_mode_count / room_modal_density	function	Mode building blocks (Long Eqs. 8.43, 8.45, 8.46). • room_mode_frequency(orders, dimensions) = (c0/2)√((nx/lx)²+(ny/ly)²+(nz/lz)²) [Hz] • room_mode_count(f, dimensions): Morse/Pierce smooth count • room_modal_density(f, dimensions) [modes/Hz]	room_mode_frequency((1, 0, 0), (7, 5, 3)) room_modal_density(1000.0, (7, 5, 3))
MODE_KINDS	constant	Mode families, strongest first: ('axial', 'tangential', 'oblique').	MODE_KINDS[0] # 'axial'
crowd_noise	function	Self-generated crowd noise vs occupancy (Long Ch. 17, Eqs. 17.50–17.52). • absorption_areas: total room absorption [m²] (scalar or 1-D) • talkers: occupancy axis N (Default: 1..20) • distance r [m] (Default: 1.2), sound_power_level Lw [dB] (Default: 70), directivity Q (Default: 2)	c = room.crowd_noise([20.0, 190.0]) • CrowdNoiseResult
CrowdNoiseResult	dataclass	Crowd self-noise result. • talkers, absorption_areas, levels [dB] (areas × talkers) • signal_level [dB], communication_level [dB], distance, sound_power_level, directivity • speech_to_noise() [dB] • .plot(): level vs occupancy per absorption	c.levels, c.signal_level c.plot()
speech_direct_level / crowd_noise_level / speech_to_noise_ratio / absorption_per_table	function	Crowd-noise building blocks (Long Eqs. 17.50–17.54). • speech_direct_level(r) = Lw + 10 lg(Q/4πr²) [dB] • crowd_noise_level(N, A) = Lw + 10 lg N + 10 lg(4/A) [dB] • speech_to_noise_ratio(r, A_tab) [dB] • absorption_per_table(r, L_SN) [m²]: the inverse	crowd_noise_level(20, 20.0) # 76 absorption_per_table(1.0, -6.0) # 6.31
NORMAL_VOICE_POWER_LEVEL / TALKER_DIRECTIVITY / COMMUNICATION_SNR / PRIVACY_SNR	constant	Crowd-noise defaults (Long Ch. 17). • 70 dB re 1 pW per talker, Q = 2 • −6 dB communication limit (Eq. 17.53), −9 dB privacy limit (Eq. 17.54)	absorption_per_table(1.0, COMMUNICATION_SNR)
sound_distribution_value / reference_distribution_value / ISO14257_REFERENCE_DISTANCE_M / FREE_FIELD_OFFSET_DB	function / constant	The curve a workroom is judged by, ISO 14257 Eqs. (1) and (2). • sound_distribution_value(levels, power_levels): D = L_p − L_W, the level at a position referred to the power of the source that made it • reference_distribution_value(distances): D_ref = 20 lg(r_0/r) − 11 dB, the free field the same source would give, with r_0 = 1 m • the 11 dB is 10 lg(4 π r_0²) rounded, which is why a free field slopes 6 dB per doubling and starts where it does	d = room.sound_distribution_value(levels, 110.8) room.reference_distribution_value([2.0, 4.0]) # -17.02, -23.04
spectrum_distribution_value / normalized_distribution_value / PINK_NOISE_WEIGHTS_DB / NORMALIZED_OFFSET_DB	function / mapping / constant	The six bands collapsed into one number, Eqs. (3) and (4). • spectrum_distribution_value(values, machine_power_levels): the curve weighted by the spectrum of the machine that will stand there • normalized_distribution_value(values): the same sum with A-weighted pink noise fixed as the spectrum, Table 1, minus the printed 6,2 dB; the six printed weights sum to 6,251 5 dB, so a flat curve comes back 0,05 dB high, and spectrum_distribution_value(values, list(PINK_NOISE_WEIGHTS_DB.values())) is the exact normalisation Annex C used • 4.2.3 says why that spectrum is a normalisation and not an average machine: real spectra are too varied for an average to mean anything	room.normalized_distribution_value(d_by_band)
spatial_decay_rate / DECADE_TO_DOUBLING	function / constant	DL2, the rate of spatial decay per distance doubling, Eq. (5). • the least-squares slope of D against lg r, times 0,3, sign flipped so a decay is positive • 6 dB is the free field; a workroom gives less, and how much less is what the room is worth • DECADE_TO_DOUBLING is the printed 0,3, which is lg 2 rounded	room.spatial_decay_rate(d, distances) # 4.39
level_excess / mean_level_excess / level_excess_at / EVALUATION_DISTANCES_M	function / mapping	DLf, how far the room sits above a free field, Eqs. (6) to (8). • level_excess: D − D_ref at every position • mean_level_excess: the average of Eq. (7), a trapezoid over lg r, so the wide gaps of a logarithmic distribution weigh what they should • level_excess_at: the height of the fitted line over the free-field line at one distance, which a single outlying position moves much less • EVALUATION_DISTANCES_M: 4 m, 10 m and 30 m, the conventional distances 6.4.3 reads the line at	room.mean_level_excess(d, distances) # 6.73
spatial_decay_curve / SpatialDecayResult	function / dataclass	One region of the path, with both descriptors, clause 6. • region: 'near', 'middle', 'far' or 'whole'; near_limit_m d₁ and far_limit_m d₂ place the boundaries • result: distances_m, distribution_values_db, reference_values_db, level_excess_db, decay_rate_db, mean_excess_db, region, band_hz • .plot(): the curve, the free field it is judged by, and the fitted slope	res = room.spatial_decay_curve(d, distances, region="middle") • res.decay_rate_db, res.mean_excess_db
distance_region / NEAR_REGION_START_M / TYPICAL_NEAR_LIMIT_M / TYPICAL_FAR_LIMIT_M / PREFERRED_MIDDLE_LIMIT_M	function / constant	The three distance ranges of 6.2. • near from 1 m to d₁, middle from d₁ to d₂, far beyond d₂, with 5 m and 16 m the typical pair • the middle region is the one health and safety work reads, and 6.2 b) asks for it to reach 24 m whenever the room allows • distances are measured from the acoustical centre of the source	room.distance_region(12.0) # 'middle'
floor_reference_value / corrected_distribution_value / SOURCE_ON_FLOOR_HEIGHT_M	function / constant	Taking the source's own curve back out, Annex B. • floor_reference_value(distances, source_height_m=…, path_height_m=…): D_ref plus 10 lg(1 + r²/(r² + 4 h_S h_P)), which is Eq. (B.4)'s 3 dB for a source on the floor • corrected_distribution_value(values, measured_reference, distances, …): Eq. (B.1) swaps the measured free-field curve of that source for the theoretical one, so what is left is the room • a source is "on the floor" at 0,5 m or under, which is where the half-space form applies	room.corrected_distribution_value(d, d_free, distances, source_height_m=0.0)
omnidirectionality_tolerance_db / OMNIDIRECTIONAL_TOLERANCE_DB / OMNIDIRECTIONAL_RAMP_HZ / MAX_DIRECTIVITY_INDEX_DB / ADJACENT_BAND_LIMIT_DB / STABILITY_TOLERANCE_DB	function / constant / mapping	What makes a source fit for the test, Annex A. • ± 2 dB up to 630 Hz, a linear rise to ± 8 dB at 1 kHz and ± 8 dB from there to 5 kHz, taken across the three one-third-octave bands that span the rise • the source's own spectrum may not step more than 8 dB between adjacent one-third octaves, and its output must hold to 1 dB below 160 Hz and 0,5 dB above 200 Hz	room.omnidirectionality_tolerance_db(800.0) # 5.0
SPATIAL_DECAY_BANDS_HZ / ISO14257_MIN_SIGNAL_TO_BACKGROUND_DB / ISO14257_PREFERRED_SIGNAL_TO_BACKGROUND_DB / MIN_SOURCE_TO_WALL_M	constant	The conditions of clause 5, as numbers. • the six octave bands from 125 Hz to 4 kHz the curve is measured in • the source at least 10 dB over the background at every position; between 6 dB and 10 dB an ISO 3744 correction is made, and under 6 dB there is no measurement • the acoustical centre of the source at least 3 m from any wall or reflecting object other than the floor	room.SPATIAL_DECAY_BANDS_HZ # (125.0, ..., 4000.0)
check_background_margin / BackgroundMarginCheck	function / dataclass	Does the source stand clear of the background? 5.1.4. • levels_db with the source running and background_levels_db without it, one octave band at a time • result: margins_db, needs_correction (under 10 dB and over 6 dB, where the clause asks for the ISO 3744 correction), unusable (6 dB or less, which it offers no correction for), satisfied • the verdict is returned and never applied: the correction belongs to the standard that prints it • Emitted by room.spatial_decay: SpatialDecayWarning when any margin is under 10 dB	check = room.check_background_margin(levels, background) check.satisfied # False
SpatialDecayWarning	warning class	The measurement is outside a condition ISO 14257 states. • a region holding the two positions a regression needs and no more, so the rate is the line through them (5.3.2) • a margin over the background under the 10 dB of 5.1.4 • level_excess_at reading the fitted line outside the distances it was fitted over, which the 30 m of 6.4.3 asks of a path that stops at 24 m • Emitted by room.spatial_decay	warnings.simplefilter('error', SpatialDecayWarning)
prediction_method / PREDICTION_METHODS / PredictionMethod	function / mapping / dataclass	The four ways ISO 11690-3 lets you predict a workroom, Table 4. • '1' is the diffuse-field method, for a room whose field may be treated as diffuse; '2a', '2b' and '2c' are geometrical, in growing order of what they model • PredictionMethod: category, family, rooms, and the detail levels Table E.1 asks it to be fed (room_detail, fitting_detail, source_detail)	room.prediction_method("2b").family # 'geometrical'
detail_is_sufficient / DetailVerdict / RECOMMENDED_DETAIL	function / dataclass / mapping	Whether the data in hand is what the method asks for, Table E.1. • detail_is_sufficient(category, room_detail=…, fitting_detail=…, source_detail=…) • verdict: satisfied, and room_ok / fittings_ok / sources_ok so a refusal says which of the three is short • the annex is a recommendation, so this reports rather than raises	room.detail_is_sufficient("2c", room_detail=2, fitting_detail=2, source_detail=1)
ROOM_DETAIL_LEVELS / FITTING_DETAIL_LEVELS / SOURCE_DETAIL_LEVELS	mapping	How much of the room, the fittings and the sources a model carries, Tables 1 to 3. • room: from the volume and one mean absorption coefficient up to the actual shape with absorption distributed over it • fittings: from ignored up to their real shape and location, with shielding and reflection • sources: omnidirectional points, points with a directivity, complex sources	room.ROOM_DETAIL_LEVELS[2]
fitting_density	function	q = S/4V, the density of the fittings, NOTE 3 of 6.2.2. • surface_area_m2: the total surface of everything standing in the room • volume_m3: the volume they stand in	room.fitting_density(480.0, 1200.0) # 0.1
workstation_level_increase / workstation_level / total_workstation_level	function	What the room adds at the machine's own workstation, Annex C. • workstation_level_increase(sound_power_level_db=…, emission_level_db=…, absorption_area_m2=…): 10 lg(1 + 4S/A) with S = 10^((L_WA − L_pA)/10), the room reflecting back what the machine emits • workstation_level: the emission level with that increase on it • total_workstation_level(contributions, existing_level_db=…): the energy sum of every machine, and of what was already there	room.workstation_level(sound_power_level_db=95.0, emission_level_db=85.0, absorption_area_m2=200.0)
typical_decay_range / typical_excess_range / TYPICAL_DECAY_RANGE_DB / TYPICAL_EXCESS_RANGE_DB	function / mapping	What 4.3 says the two descriptors usually are, region by region. • DL2: 5 dB to 6 dB near, 2 dB to 5 dB in the middle, over 6 dB far away • DLf: 2 dB to 10 dB in the middle region, which is the one the clause prints a range for • an open bound comes back as None, so a range is a pair to read rather than a limit to enforce	room.typical_decay_range("middle") # (2.0, 5.0)
airborne_insulation	function	Field airborne insulation (ISO 16283-1). • l1/l2: Source/receiving levels [dB], 1D or (positions, bands) • t2: Receiving-room T per band [s] • area: Partition S [m²] (for R') • volume: Receiving V [m³] (for R') • t0: Reference T0 [s] (Default: 0.5) • frequencies [Hz] (required with either low-frequency argument) • source_low_frequency / receiver_low_frequency: LowFrequencyProcedure per room (ISO 16283-1 Clause 8) • Warns (LowFrequencyWarning) when volume rounds below 25 m³, frequencies names 50/63/80 Hz and no receiver_low_frequency is given	ins = building.airborne_insulation(l1, l2, t2, area=10, volume=50) • AirborneInsulationResult
weighted_rating	function	Single-number rating + C/Ctr (ISO 717-1). • values_by_band: 16 thirds or 5 octaves [dB] • bands: 'third-octave', 'octave' or None	w = building.weighted_rating(R) • WeightedRatingResult (Rw, C, Ctr)
weighted_rating_extended	function	Rating + enlarged-range terms (ISO 717-1 Annex B). • values_by_band [dB] with frequencies [Hz] (None = the 16 core bands) • one_decimal: 0.1 dB shift + one-decimal reductions for uncertainty statements (Default: False)	ext = building.weighted_rating_extended(r, freqs) • ExtendedWeightedRatingResult (rating, c, ctr, c_50_3150 … ctr_100_5000)
ExtendedWeightedRatingResult	dataclass	Weighted rating with the enlarged-range adaptation terms (ISO 717-1 Annex B). • rating + c, ctr • c_50_3150, c_50_5000, c_100_5000 and the ctr_ twins • core: the base WeightedRatingResult	res = building.weighted_rating_extended(freqs, r)
db_hr_global_index	function	A-weighted global index Ix = −10 lg Σ 10^((Lx,i−Xi)/10) (CTE DB-HR Annex A, A.5-A.7). • band_values Xi [dB] over the 18 bands 100 Hz-5 kHz • spectrum: 'pink','traffic','railway','aircraft' • frequencies [Hz], name	idx = building.db_hr_global_index(r, "pink") • DbHrGlobalIndexResult
ra	function	RA for pink noise (DB-HR Annex A). • reduction_index R or R' [dB]; frequencies	ra(r_prime).intermediate # 51.4 dBA
ra_tr	function	RA,tr for road-traffic noise (DB-HR Annex A). • reduction_index [dB]; frequencies	ra_tr(r).reported
dnt_a	function	DnT,A between rooms, pink noise (Formula A.7). • level_difference DnT [dB]; frequencies	dnt_a(dnt).reported
d2m_nt_a	function	D2m,nT,A of a facade (Formula A.5). • level_difference D2m,nT [dB]; frequencies • spectrum: 'pink' (Default) or 'railway' • Clause 3.1.3.4 point 1: the quantity a railway-dominant site is assessed in	d2m_nt_a(d, spectrum='railway').name # 'D2m,nT,A'
d2m_nt_atr	function	D2m,nT,Atr of a facade (Formula A.6). • level_difference D2m,nT [dB]; frequencies • spectrum: 'traffic' (Default) or 'aircraft' • Railway noise is D2m,nT,A via (A.5): use d2m_nt_a	d2m_nt_atr(d).intermediate # 32.8 dBA
DbHrGlobalIndexResult	dataclass	A DB-HR A-weighted global index. • value (exact), intermediate (1 decimal), reported (integer, 3.1.3.1 point 4) • name, spectrum, reference • frequencies, band_values, spectrum_levels, band_contributions • .plot()	idx.value, idx.intermediate, idx.reported
DB_HR_FREQUENCIES	constant	The eighteen 1/3-octave centres of DB-HR Annex A, 100 Hz to 5 kHz.	DB_HR_FREQUENCIES[0] # 100.0
DB_HR_NORMALISED_SPECTRA	constant	Normalised A-weighted source spectra [dBA] of Annex A Tables A.2-A.5. 'pink' (A.5), 'traffic' (A.3), 'railway' (A.4, equal to A.3), 'aircraft' (A.2)	DB_HR_NORMALISED_SPECTRA["pink"]
window_size_correction	function	Window-size correction of RA / RA,tr [dB] (CTE Catálogo de Elementos Constructivos). • area [m²]: 0 up to 2,7; −1 to 3,6; −2 to 4,6; −3 above	26 + building.window_size_correction(4.0) # 24 dBA
db_hr_facade_requirement	function	Required D2m,nT,Atr (DB-HR Table 2.1). • ld [dBA], building_use, room_type • dominant_noise: 'road','railway','aircraft' (+4 dBA) • quiet_facade: assess with Ld − 10 dBA	db_hr_facade_requirement(62, "residential", "bedrooms") # 32 dBA
db_hr_airborne_requirement	function	Airborne requirements between rooms (DB-HR 2.1.1). • receiving_room: 'protected'/'habitable' • source_room: 'same_unit','other_unit','installations','activity' • shared_opening: the RA pair on the door/window and its enclosure	(req,) = building.db_hr_airborne_requirement("protected", "other_unit") # 50 dBA
db_hr_party_wall_requirement	function	Party wall between two buildings (DB-HR 2.1.1 c), alternatives. • quantity: 'D2m,nT,Atr' (40 dBA per leaf) or 'DnT,A' (50 dBA for both)	db_hr_party_wall_requirement()
db_hr_impact_requirement	function	Impact requirement L'nT,w (DB-HR 2.1.2). • receiving_room, source_room (65 dB against another use unit, 60 dB otherwise)	db_hr_impact_requirement("protected", "other_unit") # ≤ 65 dB
db_hr_reverberation_requirement	function	Reverberation / absorption requirement (DB-HR 2.2). • room_use: 'classroom','restaurant','common_area' (or aliases) • furnished: classroom with seating (0,5 s)	db_hr_reverberation_requirement("classroom") # ≤ 0.7 s
DbHrRequirement	dataclass	A single DB-HR performance requirement. • quantity, limit, direction ('min'/'max'), unit • decimals: rounding before the comparison • reference, description	req.quantity, req.limit
check_db_hr_requirement	function	Check an achieved value against a requirement. • value, requirement • Rounds as DB-HR prescribes, then compares	check_db_hr_requirement(32.8, req) • DbHrCheck
DbHrCheck	dataclass	A DB-HR requirement checked. • requirement, value, reported, margin, complies	chk.reported, chk.complies
assess_db_hr	function	Check a set of (value, requirement) pairs. • items	assess_db_hr([(33.0, req)]) • DbHrAssessment
DbHrAssessment	dataclass	A set of DB-HR requirement checks. • checks; .complies • .plot()	a.complies
energy_average_level	function	Energy-average level (ISO 16283-1 (9)). • levels: Levels [dB] to average • axis: Averaging axis (Default: -1)	L = building.energy_average_level([60, 66]) • 10 lg( mean(10^(Li/10)) )
AirborneInsulationResult	dataclass	Field insulation per band. • d: Level difference D [dB] • dnt: Standardized DnT [dB] • r_prime: Apparent R' [dB] or None • l1, l2, t2, t0: retained measurement chain (or None) • source_low_frequency, receiver_low_frequency: LowFrequencyResult or None • .report(path, quantity='dnt'/'r_prime', ...): ISO 16283-1 field test report (Annex B form) with the ISO 717-1 rating → PDF	res.report("DnTw.pdf", metadata=ReportMetadata(requirement=50.0))
WeightedRatingResult	dataclass	Weighted rating result. • rating: Rw/DnT,w … [dB], int • c: Spectrum term C, int • ctr: Spectrum term Ctr, int • unfavourable_sum: [dB] • band_centers: Measured-curve centres [Hz] or None • measured: Measured band values [dB] or None • shifted_reference: Shifted Table 3 reference [dB] or None	w.rating, w.c, w.ctr
impact_insulation	function	Field impact insulation (ISO 16283-2). • li: Impact SPL [dB], 1D or (positions, bands) • t2: Receiving-room T per band [s] • volume: Receiving V [m³] (for L'n) • t0: Reference T0 [s] (Default: 0.5) • frequencies [Hz] (required with low_frequency) • low_frequency: receiving-room LowFrequencyProcedure (ISO 16283-2 Clause 8) • Warns (LowFrequencyWarning) when volume rounds below 25 m³, frequencies names 50/63/80 Hz and no low_frequency is given	imp = building.impact_insulation(li, t2, volume=50) • ImpactInsulationResult (l_n_t, l_n)
weighted_impact_rating	function	Single-number impact rating + CI (ISO 717-2). • values_by_band: 16 thirds (100-3150 Hz) or 5 octaves (125-2000 Hz) [dB] • bands: 'third-octave', 'octave' or None	r = building.weighted_impact_rating(imp.l_n_t) • ImpactRatingResult (Ln,w, CI); octave rating carries the -5 dB rule
weighted_impact_rating_extended	function	Impact rating + CI,50-2500 (ISO 717-2:2020 A.2.1 NOTE). • values_by_band [dB] with frequencies [Hz] (None = the 16 core bands) • one_decimal: 0.1 dB shift (reproduces Ln,r,0,w = 77.6, CI,r,0 = -10.3 of A.2.2) (Default: False)	ext = building.weighted_impact_rating_extended(ln, freqs) • ExtendedImpactRatingResult (rating, ci, ci_50_2500)
ExtendedImpactRatingResult	dataclass	Weighted impact rating with CI,50-2500 (ISO 717-2:2020 A.2.1). • rating, ci, ci_50_2500 • core: the base ImpactRatingResult	res = building.weighted_impact_rating_extended(freqs, ln)
weighted_impact_improvement	function	Weighted improvement ΔLw (ISO 717-2 §5). • delta_l: 16 one-third-octave ΔL (100-3150 Hz) [dB] Applies the Table 4 reference floor: ΔLw = 78 − Ln,r,w	weighted_impact_improvement(delta_l) • ΔLw [dB] (e.g. 19)
impact_improvement_adaptation_term	function	Spectrum adaptation term CI,Δ (ISO 717-2:2020 Formula (A.4)). • delta_l: 16 one-third-octave ΔL (100-3150 Hz) [dB] CI,Δ = CI,r,0 − CI,r (CI,r,0 = −11 dB); ISO 16251-1 clause 8 e)	impact_improvement_adaptation_term(delta_l) • CI,Δ [dB], int
impact_improvement	function	Floor-covering improvement ΔL (ISO 16251-1). • bare, with_covering: acceleration levels L0/L1 per band [dB] • frequencies [Hz] (a clause 6.3 spectrum is rated on its 100-3150 Hz sub-range) • background: optional Lb per band [dB] (Formula 2)	res = building.impact_improvement(l0, l1, f) • FloorCoveringImprovementResult
acceleration_level	function	Vibratory acceleration level La (ISO 16251-1 Formula 1). • acceleration: RMS a per band [m/s²] • reference: a0 (Default: 1e-6)	acceleration_level(1e-3) # 60 dB
background_corrected_level	function	Background correction (ISO 16251-1 Formula 2). • signal_and_background, background [dB]	L, limited = building.background_corrected_level(lp, lb) • (corrected [dB], limit-of-measurement mask)
improvement_octave_bands	function	Thirds → octaves for ΔL (ISO 16251-1 Formula 5). • improvement, frequencies (whole octave triplets)	f_oct, dl_oct = building.improvement_octave_bands(dl, f)
FloorCoveringImprovementResult	dataclass	Floor-covering improvement (ISO 16251-1). • improvement ΔL [dB], delta_lw, ci_delta (or None) • limited: > ΔL mask; .octave_bands(), .plot()	res.delta_lw, res.ci_delta
ImpactInsulationResult	dataclass	Impact insulation per band. • l_n_t: Standardized L'nT [dB] • l_n: Normalized L'n [dB] or None • li, t2, t0: retained measurement chain (or None) • low_frequency: LowFrequencyResult or None • .report(path, quantity='l_n_t'/'l_n', ...): ISO 16283-2 field test report (Annex C form) with the ISO 717-2 rating → PDF	imp.report("LnTw.pdf", metadata=ReportMetadata(requirement=58.0))
ImpactRatingResult	dataclass	Weighted impact rating. • rating: Ln,w/L'n,w/L'nT,w [dB], int • ci: Spectrum term CI, int • unfavourable_sum: [dB] • band_centers: Measured-curve centres [Hz] or None • measured: Measured impact levels [dB] or None • shifted_reference: Shifted impact reference [dB] or None	r.rating, r.ci
ReportMetadata	dataclass	Metadata for the accredited ISO 717 .report() PDF fiche. • All fields optional; only the supplied ones render • specimen, client, manufacturer, test_room, instrumentation, calibration, mounting, measurement_standard, test_date • numeric (finite, positive): area, mass_per_area, source_volume, receiving_volume, temperature_c, relative_humidity_percent, static_pressure_kpa, requirement • laboratory, operator, report_id, notes	w.report("f.pdf", metadata=ReportMetadata(area=10.0, requirement=52.0))
facade_insulation	function	Field façade insulation (ISO 16283-3). • l1_2m/l2: Level 2 m in front / receiving levels [dB], 1D or (positions, bands) • t2: Receiving-room T per band [s] • area: Element S [m²], volume: Receiving V [m³], surface_level: L1,s [dB] (all three for R') • method: 'loudspeaker' (−1.5 dB) / 'road_traffic' (−3 dB) • t0: Reference T0 [s] (Default: 0.5) • frequencies [Hz] (required with low_frequency) • low_frequency: receiving-room LowFrequencyProcedure (ISO 16283-3 Clause 7.3); loudspeaker methods only • Warns (LowFrequencyWarning) when a loudspeaker-method volume rounds below 25 m³, frequencies names 50/63/80 Hz and no low_frequency is given	fac = building.facade_insulation(l1_2m, l2, t2, volume=50, area=11.5, surface_level=ls) • FacadeInsulationResult
FacadeInsulationResult	dataclass	Façade insulation per band. • d_2m: Level difference D2m [dB] • d_2m_nt: Standardized D2m,nT [dB] • d_2m_n: Normalized D2m,n [dB] or None • r_prime: Apparent R'45°/R'tr,s [dB] or None • frequencies [Hz] or None • method: the incidence correction used • low_frequency: LowFrequencyResult or None • .plot()	fac.d_2m_nt, fac.r_prime
LowFrequencyProcedure	dataclass	ISO 16283 low-frequency measurements of one room (Clause 8 / 7.3). • volume: Room V [m³]; must round below 25 m³ • corner_levels: (corners, 3) or (positions, corners, 3) at 50/63/80 Hz [dB] • reverberation_63_octave: 63 Hz octave T [s] (receiving room, Clause 10.4 / 8.4)	lf = building.LowFrequencyProcedure(volume=18.0, corner_levels=c, reverberation_63_octave=0.72)
low_frequency_procedure_applies	function	The printed 25 m³ trigger. • volume: Room V [m³], rounded to the nearest cubic metre (half away from zero) • True only for a rounded volume strictly below 25 m³	building.low_frequency_procedure_applies(18.0) # True
corner_level	function	Corner level L_Corner (ISO 16283-1 (12) / -2 (15)). • corner_levels: (corners, bands) or (positions, corners, bands) [dB] • Highest corner per band, then energy-averaged over source positions	lc = building.corner_level(corners)
low_frequency_level	function	Combination L_LF (ISO 16283-1 (13) / -2 (16) / -3 (5)). • level: Default-procedure L [dB] • corner: L_Corner [dB] • 10 lg[(10^(0,1 Lc) + 2·10^(0,1 L))/3]	llf = building.low_frequency_level(l, lc)
apply_low_frequency_procedure	function	Run the procedure over a whole band vector. • level, frequencies, procedure • reverberation_time: measured T per band (receiving room) • room: 'receiving' (Clause 10.4 applies) or 'source'	res = building.apply_low_frequency_procedure(l2, f, lf, reverberation_time=t2)
LowFrequencyResult	dataclass	What the procedure did to one room. • levels, reverberation_time: full band vectors after substitution • l_default, l_corner, l_lf: the three-band chain [dB] • low_frequency_bands [Hz], volume [m³], reverberation_63_octave [s] • .plot()	res.l_lf, res.reverberation_time
LOW_FREQUENCY_BANDS	tuple	The three one-third-octave bands the procedure covers (50, 63, 80 Hz).	building.LOW_FREQUENCY_BANDS
LOW_FREQUENCY_VOLUME_LIMIT	float	Room volume the procedure stops at, 25 m³ to the nearest cubic metre, strictly.	building.LOW_FREQUENCY_VOLUME_LIMIT # 25.0
LowFrequencyWarning	warning class	An ISO 16283 low-frequency requirement the measurement does not meet. • Fewer corners than the printed minimum of four; the arithmetic is unaffected • A room under the 25 m³ trigger whose 50/63/80 Hz bands are about to be answered from the default procedure alone, which Clause 8.1 forbids and which does move the number • Filter the two apart by message, not by class	warnings.simplefilter('error', building.LowFrequencyWarning) Emitted by building.measurement.low_frequency
lab_airborne_insulation	function	Laboratory airborne insulation (ISO 10140-2). • l1/l2: Source/receiving levels [dB], 1D or (positions, bands) • t2: Receiving-room T per band [s] • area: Free test-opening S [m²] • volume: Receiving V [m³]	lab = building.lab_airborne_insulation(l1, l2, t2, area=10, volume=50) • LabAirborneInsulationResult
lab_impact_insulation	function	Laboratory impact insulation (ISO 10140-3). • li: Tapping-machine impact SPL [dB], 1D or (positions, bands) • t2: Receiving-room T per band [s] • volume: Receiving V [m³]	imp = building.lab_impact_insulation(li, t2, volume=50) • LabImpactInsulationResult
intensity_sound_reduction	function	Intensity sound reduction index RI (ISO 15186-1 Formula (7)). • lp1: Source-room level [dB], 1D or (positions, bands) • l_in: Normal intensity level over the surface [dB] • measurement_area: Surface Sm [m²], area: Specimen S [m²] • kc: Adaptation term per band [dB] for RI,M (Default: None)	res = building.intensity_sound_reduction(lp1, l_in, measurement_area=12, area=10) • IntensityReductionResult (r_i, r_i_modified, rating, rating_modified)
adaptation_term_kc	function	Adaptation term Kc (ISO 15186-1 Annex B). • frequencies: Midband frequencies [Hz] • boundary_area/volume: Room Sb2/V2 for Formula (B.1); omit both for the 10 lg(1+61,4/f) approximation (B.2)	kc = building.adaptation_term_kc(freqs) • Kc per band [dB]
intensity_element_normalized_difference	function	Intensity element normalized level difference DI,n,e (ISO 15186-1 Formula (8)). • lp1/l_in: Source level / surface intensity level [dB] • measurement_area: Surface Sm [m²] • n: Element units N (Default: 1)	d = building.intensity_element_normalized_difference(lp1, l_in, measurement_area=10) • IntensityElementNormalizedResult (d_i_n_e, rating)
surface_pressure_intensity_indicator / combine_subareas	function	Surface indicator FpI and subarea combination (ISO 15186-1 Formulas (10)-(12)). • lp/l_in: Surface pressure / intensity levels [dB] • combine_subareas(l_in, measurement_area): (subareas, bands) levels + per-subarea areas (negative area = reverse-flow subarea, Clause 6.4.6)	fpi = building.surface_pressure_intensity_indicator(lp, l_in) • FpI array; (LIn, Sm = Σ abs(Smi))
IntensityReductionResult / IntensityElementNormalizedResult	dataclass	ISO 15186-1 intensity insulation results. • r_i / r_i_modified per band with rating / rating_modified • d_i_n_e per band with rating	res = building.intensity_sound_reduction(...)
low_frequency_intensity_reduction	function	Low-frequency intensity sound reduction index RI (ISO 15186-3 Formula (7)). • lp_surface: Level over the surface of the specimen [dB], 1D or (positions, bands) • l_in: Normal intensity level over the measurement surface [dB] • measurement_area: Surface Sm [m²], area: Specimen S [m²] • l_p: Receiving-side pressure on the measurement surface [dB] for FpI (Default: None) • frequencies: 50 Hz to 160 Hz only (Clause 6.6) (Default: None) • absorbing_specimen_surface: Tightens the Clause 6.4.2 limit to 6 dB (Default: False)	res = building.low_frequency_intensity_reduction(lps, l_in, measurement_area=12.6, area=10) • LowFrequencyIntensityResult (r_i, surface_pressure_intensity_indicator, qualified, indicator_limit)
low_frequency_element_normalized_difference	function	Low-frequency element normalized level difference DI,n,e (ISO 15186-3 Formula (8)). • lp_surface/l_in: Surface level / measurement-surface intensity level [dB] • measurement_area: Surface Sm [m²] • elements: Element units N, added as +10 lg N (Default: 1) • l_p: Receiving-side pressure on the measurement surface [dB] for FpI (Default: None) • frequencies: 50 Hz to 160 Hz only (Clause 1.1) (Default: None) • absorbing_specimen_surface: Tightens the Clause 6.4.2 limit to 6 dB (Default: False)	d = building.low_frequency_element_normalized_difference(lps, l_in, measurement_area=2.0) • LowFrequencyElementResult (d_i_n_e, surface_pressure_intensity_indicator, qualified, indicator_limit)
limp_panel_reduction_index	function	Calculated limp-panel sound reduction index (ISO 15186-3 Annex A, Formulas (A.1)-(A.5)). • frequencies: Mid-band frequencies [Hz] • surface_mass: Panel mass m [kg/m²], area: Panel S [m²] (≥ 1 m²) • temperature_c/static_pressure_pa: Climate of (A.4) and (A.5) (Default: 23 °C, 101 300 Pa)	r = building.limp_panel_reduction_index(freqs, surface_mass=10.0, area=10.0) • R array [dB]; a measurement must agree within 4,0 dB from 50 Hz to 160 Hz
LowFrequencyIntensityResult / LowFrequencyElementResult	dataclass	ISO 15186-3 low-frequency intensity results. • r_i / d_i_n_e per band, no rating (six bands cannot feed ISO 717-1) • surface_pressure_intensity_indicator and qualified, or None when l_p was not given • indicator_limit: The Clause 6.4.2 limit the bands were judged by, 10 dB or 6 dB	res = building.low_frequency_intensity_reduction(...)
reverberation_index / estimate_reverberation_index	function	Survey reverberation index k (ISO 10052:2021 Clause 3.3 / Table 4). • reverberation_index(t): k = 10 lg(T/0.5) per band • estimate_reverberation_index(volume, room): k from Table 4 (room: kitchen/bathroom/furnished/a-h/a+e...); weighted=True for the A/C column	k = building.reverberation_index(t) • k per band [dB]
survey_airborne_insulation	function	Survey airborne insulation (ISO 10052:2021 Clauses 3.2-3.6). • l1/l2: source/receiving levels [dB] • reverberation_index: k per band [dB] • volume (for Dn/R'), area (R', V/7.5 rule)	res = building.survey_airborne_insulation(l1, l2, k, volume=50, area=12) • SurveyAirborneResult (d, d_nt, d_n, r_prime, rating, r_prime_rating)
survey_impact_insulation / survey_facade_insulation	function	Survey impact & façade insulation (ISO 10052:2021 Clauses 3.7-3.9 / 3.13-3.15). • li (impact) or l1_2m/l2 (façade), reverberation_index, volume	imp = building.survey_impact_insulation(li, k, volume=50) • SurveyImpactResult / SurveyFacadeResult
survey_service_equipment_level	function	Service-equipment noise LXY (ISO 10052:2021 Clauses 3.16-3.18). • measurements: three A/C-weighted positions [dB] • reverberation_index: k (scalar or per band) • volume (for LXY,n)	se = building.survey_service_equipment_level([35, 30, 32], 3.0, volume=50) • SurveyServiceEquipmentResult (l_xy, l_xy_nt, l_xy_n)
SurveyAirborneResult / SurveyImpactResult / SurveyFacadeResult / SurveyServiceEquipmentResult	dataclass	ISO 10052 survey-method results. • per-band quantities (d, d_nt, d_n, r_prime; l_i, l_nt, l_n; d_2m...; l_xy...) • weighted rating where the method defines one	res = building.survey_airborne_insulation(...)
background_correction	function	Background-noise correction (ISO 10140-4 §4.3). • signal_and_background: Combined Lsb per band [dB] • background: Lb per band [dB] • 6–15 dB margin corrected, ≤6 dB capped at 1.3 dB, ≥15 dB unchanged	L = building.background_correction(lsb, lb) • Corrected levels [dB] (LabInsulationWarning at the limit of measurement)
LabAirborneInsulationResult	dataclass	Laboratory airborne result. • r: Sound reduction index R [dB] • absorption: A = 0.16 V/T [m²] • rating: WeightedRatingResult or None • .plot() (needs the rating) • .report(path, ...): ISO 10140-2 laboratory test report with the ISO 717-1 rating → PDF (also needs the rating; 16 one-third-octave or 5 octave bands)	lab.r, lab.rating.rating
LabImpactInsulationResult	dataclass	Laboratory impact result. • l_n: Normalized impact level Ln [dB] • absorption: A [m²] • rating: ImpactRatingResult or None • .plot() (needs the rating) • .report(path, ...): ISO 10140-3 laboratory test report with the ISO 717-2 rating → PDF (also needs the rating; 16 one-third-octave or 5 octave bands)	imp.l_n, imp.rating.rating
LabInsulationWarning	warning class	Limit-of-measurement condition (ISO 10140-4). Emitted by background_correction when a band's signal-to-background margin is ≤ 6 dB (fixed 1.3 dB cap applied)	warnings.simplefilter('error', LabInsulationWarning)
predicted_airborne_insulation	function	Predicted apparent airborne R'w (EN 12354-1 Formula 26). • r_direct: Separating-element Rs,w [dB] • flanking_paths: sequence of FlankingPath (Default: ()) • delta_r_direct: Lining ΔRDd,w [dB] (Default: 0)	res = building.predicted_airborne_insulation(r_direct=57, flanking_paths=paths) • AirbornePredictionResult
predicted_impact_insulation	function	Predicted apparent impact L'n,w (EN 12354-2 Formula 21). • ln_w_eq: Bare-floor equivalent Ln,w,eq [dB] • delta_l_w: Covering improvement ΔLw [dB] (Default: 0) • k_correction: Flanking K [dB] (Default: 0)	imp = building.predicted_impact_insulation(ln_w_eq=76.2, delta_l_w=33, k_correction=2) • ImpactPredictionResult
junction_vibration_reduction	function	Vibration reduction index Kij (EN 12354-1 Annex E.3-E.9). • junction_type: 'rigid_cross'/'rigid_t'/'flexible_t'/'lightweight_facade'/'lightweight_double_homogeneous'/'lightweight_double_coupled'/'corner'/'thickness_change' • path: 'through' (K13) / 'corner' (K12=K23) / 'double_leaf' (K24) • mass_ratio: m'⊥,i/m'i • frequency [Hz] (Default: 500), f1 [Hz] (Default: 125)	k = building.junction_vibration_reduction('rigid_cross', 'through', 1.61) • Kij [dB]
junction_min_vibration_reduction	function	Minimum Kij,min (EN 12354-1 Formula 29). • coupling_length: lf [m] • s_i, s_j: Element areas [m²]	kmin = building.junction_min_vibration_reduction(4.5, 11.5, 11.5) • Kij,min [dB]
flanking_path	function	One flanking path Rij,w (EN 12354-1 Formula 28a). • label, kind: 'Ff'/'Df'/'Fd' • r_source/r_receive: element indices [dB] • k_ij [dB], separating_area Ss [m²], coupling_length lf [m] • delta_r [dB] (Default: 0), kij_min [dB] clamp (Default: None)	p = building.flanking_path(label='f', kind='Ff', r_source=49, r_receive=49, k_ij=12.4, separating_area=11.5, coupling_length=4.5) • FlankingPath
flanking_element	function	The three paths (Ff, Df, Fd) of one flanking element. • label, r_flanking, r_separating [dB] • k_ff/k_fd/k_df [dB] • separating_area Ss [m²], coupling_length lf [m] • delta_r_ff/delta_r_fd/delta_r_df [dB] (Default: 0) • flanking_area SF [m²] (Default: None): enables the automatic Kij,min clamp (Clause 4.4.2 / Formula 29)	ff, df, fd = building.flanking_element(label='floor', r_flanking=49, r_separating=57, k_ff=12.4, k_fd=8.9, k_df=8.9, separating_area=11.5, coupling_length=4.5)
combine_linings	function	Combine two lining improvements (EN 12354-1 Formulas 30/31). • delta_a, delta_b [dB] (pass 0 for a single lining)	dr = building.combine_linings(14.0, 14.0) • max(a,b) + min(a,b)/2 = 21.0 [dB]
equivalent_impact_level	function	Bare-floor equivalent Ln,w,eq (EN 12354-2 Annex B). • mass_per_area: m' [kg/m²]	lneq = building.equivalent_impact_level(322.0) • 164 − 35 lg(m') = 76.2 [dB]
impact_flanking_correction	function	Flanking correction K (EN 12354-2 Table 1). • separating_mass, flanking_mass [kg/m²] (nearest tabulated)	k = building.impact_flanking_correction(322.0, 145.0) • K = 2 [dB], int
standardized_impact_level	function	Standardized L'nT,w (EN 12354-2 Formula 3, exact 0.032·V form). • l_prime_n_w: L'n,w [dB] • volume: Receiving V [m³] (Annex E.3's V/30 is the standard's own rounding)	lnt = building.standardized_impact_level(45.2, 50.0) • L'nT,w = 43.2 [dB]
standardized_level_difference	function	DnT,w from R'w (EN 12354-1 Formula 5b, exact 0.32·V/Ss form). • r_prime_w: R'w [dB] • volume V [m³], separating_area Ss [m²]	dnt = building.standardized_level_difference(52.2, 50.0, 11.5) • DnT,w = 53.6 → 54 [dB]
facade_sound_reduction	function	Predicted façade insulation D2m,nT (EN 12354-3 Formula 10/13). • elements: sequence of FacadeElement • area: Façade S [m²], volume: Receiving V [m³] • delta_l_fs: ΔLfs [dB] (Default: 0), bands • frequencies: band centres [Hz] (Default: None; length must equal the band count), carried on the result for plotting	fac = building.facade_sound_reduction(elements, area=11.3, volume=50.0, bands="octave") • FacadePredictionResult
plot_facade_elements	function	Composite façade elevation, element areas to scale. • elements: FacadeElement sequence • language	plot_facade_elements(elements) • Also FacadePredictionResult.plot_geometry()
FacadePredictionResult	dataclass	Predicted façade airborne insulation (EN 12354-3:2000). • r_prime, r_45, r_tr_s, d_2m_nt per band • r_tr_s_w, d_2m_nt_w, c_tr single numbers	res = building.facade_sound_reduction(...)
radiated_sound_power	function	Radiated sound power LW (EN 12354-4 Formula 2/3). • elements, lp_in: Inside Lp,in [dB] • area: Segment S [m²] • c_d: Cd [dB] (Default: -6), r_prime_cap: optional R' cap [dB] (Default: None; the Annex G example footnote uses 40), octave_bands	seg = building.radiated_sound_power(elements, lp_in=lp, area=200.0, c_d=-5.0) • RadiatedPowerResult
RadiatedPowerResult	dataclass	Sound power radiated outside by a façade segment (EN 12354-4). • l_w, r_prime per band • l_w_dba: A-weighted total	res = building.radiated_sound_power(...)
outdoor_attenuation	function	Finite radiating-side attenuation A'tot (EN 12354-4 Annex E). • width, height: Side dimensions [m] • distance: Perpendicular d [m]	a = building.outdoor_attenuation(60.0, 10.0, 5.0) • A'tot = 26.3 [dB]
outdoor_level	function	Exterior level Lp (EN 12354-4 Formula E.1). • l_w: Radiated LW [dB], scalar or per-side • attenuation: A'tot [dB], scalar or per-side	lp = building.outdoor_level(62.9, 26.3) • Lp = 36.6 [dB]
facade_shape_level_difference	function	Façade-shape term ΔLfs (EN 12354-3 Annex C, Figure C.2). • shape: 'plane_facade'/'gallery_2'…'gallery_5'/'balcony_6'…'balcony_8'/'terrace_open'/'terrace_closed' • line_of_sight h [m] (Default: 0), absorption αw (Default: 0.3, interpolated)	dlfs = building.facade_shape_level_difference('balcony_6', line_of_sight=2.0, absorption=0.6) • ΔLfs = 1 [dB]
FacadeElement	dataclass	One façade transmission path (EN 12354-3/-4). • give exactly one of r: area element [dB] / dn_e: small element [dB] / insertion_loss: opening [dB] • area: Sᵢ [m²] (for r / insertion_loss)	FacadeElement("window", area=4.5, r=[23, 22, 30, 36, 37])
AirbornePredictionResult	dataclass	Predicted airborne insulation. • r_prime_w: Apparent R'w [dB] • r_direct_w: Direct RDd,w [dB] • paths: tuple of PathContribution • dominant: highest-energy path	res.r_prime_w, res.dominant.label
ImpactPredictionResult	dataclass	Predicted impact insulation. • l_prime_n_w: Apparent L'n,w [dB] • ln_w_eq, delta_l_w, k_correction [dB]	imp.l_prime_n_w
FlankingPath	dataclass	One flanking transmission path. • label, kind: 'Ff'/'Df'/'Fd' • r_ij_w: Flanking index Rij,w [dB]	p.r_ij_w
HomogeneousElement	dataclass	A Type A homogeneous element of the ISO 12354 detailed model. • label, area S [m²], length1/length2 [m] • mass_per_area m' [kg/m²], critical_frequency fc [Hz] • internal_loss_factor ηint (Default: 0.01) • perimeter_absorption Σ lk αk [m] (Default: 0) • density ρ [kg/m³] / longitudinal_velocity cL [m/s] (Default: None; enable the Formula B.10 plateau)	floor = building.HomogeneousElement('floor', 20.0, 5.0, 4.0, 484.0, 76.8, 0.005, 2.66, 2200.0, 3800.0)
in_situ_element	function	Whole in-situ chain of one element, per band (ISO 12354-1 Clause 4.2.2). • element: HomogeneousElement, frequencies [Hz] • bands: 'third'/'octave', resonant_only (Default: False) • fluid: Fluid (Default: EN_12354_AIR, the Annex A speed of sound with the Annex B density)	el = building.in_situ_element(floor, bands) (floor is a HomogeneousElement) • InSituElementResult
EN_12354_AIR	Fluid	The air the EN/ISO 12354 detailed model is written around. 340 m/s (Annex A), 1,29 kg/m³ (Annex B) • the fluid default of in_situ_element, in_situ_total_loss_factor and perimeter_absorption_coefficient • a phonometry.fluids.Fluid: pass a computed one to predict in the air of the building instead of the air of the standard	building.EN_12354_AIR.speed_of_sound # 340.0
InSituElementResult	dataclass	Per-band in-situ element description. • radiation_factor σ, forced_radiation_factor σf • total_loss_factor ηtot,situ, reverberation_time Ts,situ [s] • absorption_length asitu [m] • sound_reduction_index Rsitu [dB], impact_level Ln,situ [dB] • .plot()	el.sound_reduction_index, el.absorption_length
bending_radiation_factor	function	Radiation factor for free bending waves σ (ISO 12354-1 Formulae B.4-B.6). • frequencies [Hz], critical_frequency fc [Hz] • length1, length2 [m], speed_of_sound [m/s]	s = building.bending_radiation_factor(f, critical_frequency=76.8, length1=5.0, length2=4.0) • σ ≤ 2 per band
forced_radiation_factor	function	Radiation factor for forced waves σf (Formula B.3, Table B.1). • frequencies [Hz], length1, length2 [m], speed_of_sound	sf = building.forced_radiation_factor(f, length1=3.75, length2=2.65) • σf ≤ 2 per band
calculated_sound_reduction_index	function	R of a homogeneous element (Formulae B.2/B.10). • frequencies, mass_per_area m', critical_frequency fc • total_loss_factor, radiation_factor, forced_radiation_factor • bands, resonant_only (Default: False) • density, longitudinal_velocity (Default: None; high-frequency plateau)	r = building.calculated_sound_reduction_index(f, mass_per_area=484, critical_frequency=76.8, total_loss_factor=eta, radiation_factor=s, forced_radiation_factor=sf)
bare_floor_impact_level	function	Ln of a bare monolithic floor (ISO 12354-2 Formula B.2). • frequencies, mass_per_area m' • structural_reverberation_time Ts [s], radiation_factor σ	ln = building.bare_floor_impact_level(f, mass_per_area=484, structural_reverberation_time=ts, radiation_factor=s) • 155 − 30 lg m' + 10 lg Ts + 10 lg σ + 10 lg(f/fref)
reciprocity_impact_level	function	Ln from R by reciprocity (ISO 12354-2 Formulae B.3/B.4). • sound_reduction_index [dB], frequencies [Hz] • bands: 'third' (38) / 'octave' (43)	ln = building.reciprocity_impact_level(r, f) • R + Ln = 38 + 30 lg f
perimeter_absorption_coefficient	function	Bending-wave absorption at one border αk (Formula C.4). • critical_frequencies fc,j [Hz] of the connected elements • vibration_reduction_indices Kij [dB]	a = building.perimeter_absorption_coefficient([92.6, 92.6], [6.4, 6.4]) • Σ √(fc,j/fref)·10^(−Kij/10)
in_situ_total_loss_factor	function	ηtot,situ (Formula C.1). • frequencies, internal_loss_factor ηint, mass_per_area, area • critical_frequency, radiation_factor • perimeter_absorption Σ lk αk [m], fluid (Default: EN_12354_AIR)	eta = building.in_situ_total_loss_factor(f, internal_loss_factor=0.005, mass_per_area=484, area=20, critical_frequency=76.8, radiation_factor=s, perimeter_absorption=2.66)
laboratory_total_loss_factor	function	ηtot,lab ≈ ηint + m'/(485 √f) (Formula C.3). • frequencies, mass_per_area, internal_loss_factor (Default: 0.01)	eta = building.laboratory_total_loss_factor(f, mass_per_area=484)
structural_reverberation_time	function	Ts = 2,2/(f ηtot) (Formula C.1). • frequencies [Hz], total_loss_factor ηtot	ts = building.structural_reverberation_time(f, eta) • Ts per band [s]
in_situ_reduction_index / in_situ_impact_level	function	Laboratory → in-situ transfer (Formula 9 / Part 2 Formula 5). • sound_reduction_index or impact_level [dB] • situ_reverberation_time, laboratory_reverberation_time [s]	r = building.in_situ_reduction_index(r_lab, ts_situ, ts_lab) • R − 10 lg(Ts,situ/Ts,lab); Ln + 10 lg(...)
in_situ_equivalent_absorption_length	function	asitu = 2,2 π² S √(fref/f)/(co Ts,situ) (Formula 11). • frequencies, area S [m²], situ_reverberation_time [s], speed_of_sound	a = building.in_situ_equivalent_absorption_length(f, area=20.0, situ_reverberation_time=ts)
in_situ_velocity_level_difference	function	Dv,ij,situ = Kij − 10 lg(lij/√(ai aj)), ≥ 0 dB (Formula 10). • vibration_reduction_index Kij [dB] • coupling_length lij [m], absorption_length_i/absorption_length_j [m]	dv = building.in_situ_velocity_level_difference(6.4, coupling_length=4.0, absorption_length_i=ai, absorption_length_j=aj)
direct_reduction_index / direct_impact_level	function	Direct paths (Formula 14 / Part 2 Formula 11). • separating_index Rs,situ or floor_level Ln,situ [dB] • delta_r_source/delta_r_receiving, or delta_l/delta_l_ceiling [dB]	rdd = building.direct_reduction_index(r_situ, delta_r_source=dl) • RDd; Ln,d
flanking_reduction_index	function	Flanking Rij per band, Type A (Formula 15). • index_i, index_j [dB], velocity_level_difference Dv,ij,situ [dB] • separating_area Ss, area_i Si, area_j Sj [m²] • delta_r_i, delta_r_j [dB]	rij = building.flanking_reduction_index(index_i=ri, index_j=rj, velocity_level_difference=dv, separating_area=20.0, area_i=20.0, area_j=11.0)
flanking_impact_level	function	Flanking Ln,ij per band, Type A (ISO 12354-2 Formula 12). • floor_level Ln,situ, index_i, index_j, velocity_level_difference • area_i, area_j [m²], delta_l, delta_r_j [dB]	lnij = building.flanking_impact_level(floor_level=ln, index_i=ri, index_j=rj, velocity_level_difference=dv, area_i=20.0, area_j=11.0)
flanking_reduction_index_from_normalized_difference / flanking_impact_level_from_normalized_difference	function	Type B flanking paths from Dv,ij,n (Formula 17 / Part 2 Formula 14). • element indices [dB], normalized_velocity_level_difference [dB] • separating_area (airborne) or area_i (impact) [m²], coupling_length lij [m]	rij = building.flanking_reduction_index_from_normalized_difference(index_i=ri, index_j=rj, normalized_velocity_level_difference=dvn, separating_area=20.0, coupling_length=4.0)
flanking_reduction_index_from_flanking_level	function	Rij from a measured Dn,f (Formula 16). • flanking_level_difference Dn,f [dB] • separating_area Ss [m²], coupling_length lij [m] • laboratory_coupling_length llab [m] (4.5 ceilings, 2.5 façades) • reference_absorption_area A0 [m²] (Default: 10)	rij = building.flanking_reduction_index_from_flanking_level(dnf, separating_area=10.44, coupling_length=2.41, laboratory_coupling_length=2.5)
flanking_impact_level_from_flanking_level	function	Ln,ij from a measured Ln,f (ISO 12354-2 Formula 13). • normalized_flanking_impact_level Ln,f,ij,situ [dB] • area Si, laboratory_area Si,lab [m²] • coupling_length lij, laboratory_coupling_length llab [m]	lnij = building.flanking_impact_level_from_flanking_level(lnf, area=20.0, laboratory_area=10.0, coupling_length=4.0, laboratory_coupling_length=4.5)
resonant_sound_reduction_index	function	*R for resonant transmission only (Formula B.1/B.2).** • sound_reduction_index [dB], frequencies [Hz] • critical_frequency fc [Hz], correction [dB] (Default: 8, applied below fc)	rstar = building.resonant_sound_reduction_index(r, f, critical_frequency=2200.0)
floating_floor_improvement	function	ΔL of a floating floor (ISO 12354-2 Formulae C.1/C.3). • frequencies [Hz], resonance_frequency fo = 160 √(s'/m') [Hz] • slope: 30 (screed) or 40 (asphalt/dry)	dl = building.floating_floor_improvement(f, resonance_frequency=52.8) • 30 lg(f/fo), 0 at and below fo
hammer_impact_velocity	function	ISO tapping-machine impact velocity vo = √(2 g h) (Hopkins Eq. 3.85). • drop_height h [m] (Default: 0.04), gravity g [m/s²]	hammer_impact_velocity() • 0.886 [m/s]
plate_contact_stiffness	function	Hammer contact stiffness of a plate material K = 2 r E/(1 − ν²) (Hopkins Eq. 3.97). • youngs_modulus E [Pa] • poisson_ratio ν (Default: 0.2), radius r [m] (Default: 0.015)	k = building.plate_contact_stiffness(3.05e10) • K [N/m]
covering_contact_stiffness	function	Hammer contact stiffness of a soft covering K = E π r²/d (Hopkins Eq. 3.98). • youngs_modulus E [Pa], thickness d [m] • radius r [m] (Default: 0.015)	k = building.covering_contact_stiffness(1.4e6, 0.005) • K [N/m]
tapping_cut_off_frequency	function	Force-spectrum cut-off fco (Hopkins Eqs. 3.101/3.102). • contact_stiffness K [N/m], impedance Zdp [N.s/m] • mass m [kg] (Default: 0.5)	fco = building.tapping_cut_off_frequency(k, z) • fco [Hz], under- or over-critical branch
hammer_limiting_frequency	function	flimit = Zdp/(2 π m), above which the hammer mass limits the power input (Hopkins Eq. 3.106). • impedance Zdp [N.s/m], mass m [kg]	hammer_limiting_frequency(1637.0) • 521 [Hz]
force_pulse	function	Single-impact force pulse F1(t) (Hopkins Eqs. 3.95/3.96). • time t [s], contact_stiffness K [N/m], impedance Zdp [N.s/m] • mass m [kg], impact_velocity vo [m/s]	f = building.force_pulse(t, k, z) • F1(t) [N]
short_pulse_mean_square_force	function	F²rms = 3.9 B for a short impact (Hopkins Eq. 3.92). • frequencies [Hz], band: 'third'/'octave'	short_pulse_mean_square_force(500.0)
tapping_force_spectrum	function	Force spectrum of the ISO tapping machine (Hopkins 3.6.3.1). • frequencies [Hz], contact_stiffness K [N/m], impedance Zdp [N.s/m] • mass, impact_rate fi, impact_velocity vo, band	res = building.tapping_force_spectrum(f, k, z) • TappingForceResult
TappingForceResult	dataclass	Tapping-machine force spectrum on one walking surface. • peak_force |Fn| [N], mean_square_force [N²], power_input [W], power_input_level [dB] • cut_off_frequency, limiting_frequency [Hz], over_critical, lower_limit/upper_limit [N] • .plot()	res.cut_off_frequency, res.over_critical
covering_improvement	function	Predicted ΔL of a soft floor covering, ΔL = 20 lg(|Fn|without/|Fn|with) (Hopkins Eq. 4.114). • frequencies [Hz], covering_stiffness, plate_stiffness [N/m], impedance [N.s/m]	res = building.covering_improvement(f, kc, kp, z) • CoveringImprovementResult
CoveringImprovementResult	dataclass	Soft-covering improvement prediction. • improvement ΔL [dB], two_line (0 dB below fco, 12 dB/oct above) • cut_off_frequency, bare_cut_off_frequency [Hz], bare/covered force spectra • .plot()	res.improvement, res.two_line
floating_floor_resonance_frequency	function	fo = 160 √(s'/m') of a floating floor (ISO 12354-2 Formula C.2). • dynamic_stiffness s' [N/m³], mass_per_area m' [kg/m²]	floating_floor_resonance_frequency(8e6, 73.5) • 52.8 [Hz]
combined_dynamic_stiffness	function	s'tot = (Σ 1/s'i)⁻¹ for stacked resilient layers (ISO 12354-2 Formula C.6). • layers: s'i [N/m³]	combined_dynamic_stiffness([8e6, 8e6]) • 4e6 [N/m³]
double_floating_floor_resonances	function	The two resonances of a double floating floor (Hopkins Eq. 4.125). • lower_stiffness, lower_mass_per_area, upper_stiffness, upper_mass_per_area	double_floating_floor_resonances(7.25e6, 12.78, 7.25e6, 12.78) • (74, 194) [Hz]
weighted_floating_floor_improvement	function	ΔLw of a floating floor (ISO 12354-2 Formulae C.4/C.5). • mass_per_area m' [kg/m²], dynamic_stiffness s' [N/m³] • floor: 'screed' (C.4) or 'asphalt' (C.5)	weighted_floating_floor_improvement(73.5, 8e6) • 32.2 [dB]
floating_floor_improvement_spectrum	function	ΔL(f) of a floating floor above fo. • frequencies [Hz], resonance_frequency fo [Hz] • model: 'en12354' (30 lg), 'cremer' (40 lg) or 'cremer_hammer' (+10 lg[1 + (f/flimit)²]) • limiting_frequency, mass_per_area, dynamic_stiffness	res = building.floating_floor_improvement_spectrum(f, resonance_frequency=52.8) • FloatingFloorImprovementResult
FloatingFloorImprovementResult	dataclass	Floating-floor improvement prediction. • improvement ΔL [dB], resonance_frequency [Hz], model, slope [dB/decade] • limiting_frequency [Hz] or None, delta_lw [dB] or None • .plot()	res.improvement, res.delta_lw
resilient_mount_improvement	function	ΔL of a floating floor on discrete mounts, 30 dB/decade (Vér; Hopkins Eq. 4.118, Vigran Eq. 8.45). • frequencies [Hz], impedance Zdp1 [N.s/m], mass_per_area ρs1 [kg/m²] • loss_factor η1, mount_stiffness k [N/m], mount_density N' [1/m²]	dl = building.resilient_mount_improvement(f, impedance=3.8e5, mass_per_area=115.0, loss_factor=0.02, mount_stiffness=2e6, mount_density=4.0)
lining_resonance_frequency	function	fo of a lining on a basic element (ISO 12354-1 Formulae D.1/D.2). • base_mass_per_area m'1, lining_mass_per_area m'2 [kg/m²] • exactly one of dynamic_stiffness s' [N/m³] (D.1) or cavity_depth d [m] (D.2)	lining_resonance_frequency(51.0, 6.3, dynamic_stiffness=65e6) • 542 [Hz]
weighted_lining_improvement	function	ΔRw of an interior lining (ISO 12354-1 Table D.1). • resonance_frequency fo [Hz] (30-5000, rounded to the third-octave centre) • base_rating Rw [dB]	weighted_lining_improvement(100.0, 40.0) • 14.4 [dB]
lining_improvement	function	Single-number ratings of an additional layer (ISO 12354-1 Formulae D.3-D.7). • resonance_frequency fo [Hz] • system: 'mineral_wool' (D.3), 'foam' (D.4) or 'studs' (D.7) • anchors (D.5), glued_area %So (D.6)	res = building.lining_improvement(100.0) • LiningImprovementResult
LiningImprovementResult	dataclass	Annex D single-number ratings of an additional layer. • delta_rw, delta_ra, delta_ratr [dB], .ratings tuple • resonance_frequency [Hz], system, anchors, glued_area • .plot()	res.delta_rw, res.ratings
lining_improvement_in_situ	function	Laboratory → field transfer of a lining rating (ISO 12354-1 Formula D.8). • laboratory_improvement ΔRlab [dB], resonance_frequency fo [Hz], base_rating_in_situ Rw,situ [dB]	lining_improvement_in_situ(10.0, 100.0, 60.0)
TAPPING_HAMMER_MASS / TAPPING_DROP_HEIGHT / TAPPING_IMPACT_RATE / TAPPING_HAMMER_RADIUS	constant	ISO tapping-machine constants: hammer mass 0.5 kg, drop height 0.04 m, impact rate 10 Hz, assumed contact radius 0.015 m.	TAPPING_HAMMER_MASS # 0.5
airborne_flanking_path / impact_flanking_path	function	Build one flanking path from two in-situ elements. • label, kind ('Ff'/'Df'/'Fd', airborne only) • element_i/element_j (or floor/element_j): InSituElementResult • vibration_reduction_index Kij [dB], coupling_length lij [m] • separating_area Ss [m²] (airborne), delta_r_* / delta_l [dB]	p = building.airborne_flanking_path(label='D1', kind='Df', element_i=el, element_j=wall, vibration_reduction_index=6.4, coupling_length=4.0, separating_area=20.0) (el, wall are InSituElementResult) • BandPath
BandPath	dataclass	One per-band transmission path of the detailed model. • label, kind: 'Dd'/'Ff'/'Df'/'Fd' • values: Rij or Ln,ij per band [dB]	p.values
detailed_airborne_prediction / detailed_impact_prediction	function	Combine the paths into R' / L'n per band (ISO 12354-1 Formulae 1-4 / -2 Formula 1). • frequencies [Hz] • direct_index RDd or direct_level Ln,d [dB] • flanking_paths: sequence of BandPath, direct_label, bands	res = building.detailed_airborne_prediction(f, direct_index=rdd, flanking_paths=paths) (rdd from direct_reduction_index, paths of BandPath) • DetailedAirborneResult / DetailedImpactResult
DetailedAirborneResult / DetailedImpactResult	dataclass	Per-band detailed prediction (ISO 12354-1/-2:2017 Clause 4.2). • r_prime or l_prime_n per band [dB] • paths: tuple of BandPath (direct first), fractions: energy share per path and band • dominant: the leading path in each band • rating: WeightedRatingResult / ImpactRatingResult or None • .plot(): per-band path-contribution bars • .report(path, ...): one-page EN/ISO 12354 detailed prediction fiche → PDF	res.r_prime, res.dominant, res.rating.rating
PathContribution	dataclass	A path with its energy share. • label, kind: 'Dd'/'Ff'/'Df'/'Fd' • r_w: Path index [dB] • fraction: share of transmitted energy (0–1)	c.r_w, c.fraction
vibration_reduction_index	function	Measured vibration reduction index Kij (ISO 10848 Formula 13/14). • velocity_level_difference: direction-averaged D̄v,ij [dB] • junction_length lij [m], area_i/area_j [m²] • frequencies [Hz], structural_reverberation_time_i/_j [s] (both → Formula 13; else simplified 14) • speed_of_sound (Default: 343) • modal_overlap: per-band M; M < 0.25 bands bracketed and excluded from K̄ij (ISO 10848-4 Clause 9)	res = building.vibration_reduction_index(dbar, 4.0, 12.0, 10.0, frequencies=f, structural_reverberation_time_i=0.35, structural_reverberation_time_j=0.40) • VibrationReductionResult
direction_averaged_level_difference	function	Direction average D̄v,ij = ½(Dv,ij+Dv,ji) (ISO 10848 Formula 11). • dv_ij, dv_ji [dB]	dbar = building.direction_averaged_level_difference(dv_ij, dv_ji)
velocity_level_difference	function	Velocity level difference Dv,ij = Lv,i−Lv,j (ISO 10848 Formula 8). • source_level, receive_level [dB]	dv = building.velocity_level_difference(lv_i, lv_j)
equivalent_absorption_length	function	Equivalent absorption length aj (ISO 10848 Formula 12). • area Sj [m²], structural_reverberation_time Ts [s], frequencies [Hz] • speed_of_sound (Default: 343)	a = building.equivalent_absorption_length(10.0, 0.5, f)
total_loss_factor	function	Total loss factor η = 2.2/(f·Ts) (ISO 10848 Clause 7.3.1). • frequencies [Hz], structural_reverberation_time [s]	eta = building.total_loss_factor(f, ts)
normalized_flanking_level_difference	function	Airborne Dn,f = L1−L2−10 lg(A/A0) (ISO 10848 Formula 4). • source_level L1, receive_level L2 [dB] • absorption_area A [m²] • reference_area A0 (Default: 10)	res = building.normalized_flanking_level_difference(l1, l2, a) • FlankingLevelDifferenceResult
normalized_flanking_impact_level	function	Impact Ln,f = L2+10 lg(A/A0) (ISO 10848 Formula 5). • receive_level L2 [dB], absorption_area A [m²] • reference_area A0 (Default: 10)	res = building.normalized_flanking_impact_level(l2, a) • FlankingImpactLevelResult
vibration_reduction_index_from_flanking	function	Indirect Kij from Dn,f (ISO 10848 Clause 4.3.1). • normalized_flanking_level_difference Dn,f, reduction_index_i/_j Ri/Rj [dB] • junction_length, area_i/area_j, absorption_length_i/_j	k = building.vibration_reduction_index_from_flanking(dnf, ri, rj, 2.0, 10.0, 12.0, ai, aj) • Kij [dB]
critical_frequency	function	Thin-plate critical frequency fc = c0²/(1.8·cL·h·π) (ISO 10848 Formula 20). • longitudinal_wave_speed cL [m/s], thickness h [m] • speed_of_sound (Default: 343)	fc = building.critical_frequency(5500.0, 0.2)
strong_coupling_satisfied	function	Strong-coupling validity check (ISO 10848 Formula 15). • velocity_level_difference D̄v,ij [dB] • mass_i/mass_j [kg/m²], critical_frequency_i/_j [Hz]	ok = building.strong_coupling_satisfied(dbar, 20, 20, 100, 100) • bool per band
modal_density	function	Modal density n = π·S·fc/c0² (ISO 10848-4 Formula 5). • area S [m²], critical_frequency fc [Hz] • speed_of_sound (Default: 343)	n = building.modal_density(10.0, 200.0)
modal_overlap_factor	function	Modal overlap M = 2.2·n/Ts (ISO 10848-4 Formula 6). • area, critical_frequency, structural_reverberation_time [s]	m = building.modal_overlap_factor(10.0, 200.0, ts) # feed building.vibration_reduction_index(modal_overlap=m)
band_mode_count	function	In-band mode count N = 0.23·f·n (ISO 10848-4 Formula 4). • frequencies [Hz], area, critical_frequency	n5 = building.band_mode_count(f, 10.0, 200.0) # N≥5 OK
VibrationReductionResult	dataclass	Measured Kij (ISO 10848). • frequencies [Hz] (or None), k_ij [dB] • single_number: mean K̄ij 200–1250 Hz (thirds) / 125–1000 Hz (octaves), or None • bracketed: M < 0.25 flags (or None) • .octave_bands(), .plot()	res.k_ij, res.single_number
FlankingLevelDifferenceResult	dataclass	Normalized flanking level difference Dn,f (ISO 10848). • d_n_f [dB], rating: Dn,f,w (or None) • .plot()	res.d_n_f, res.rating
FlankingImpactLevelResult	dataclass	Normalized flanking impact level Ln,f (ISO 10848). • l_n_f [dB], rating: Ln,f,w (or None) • .plot()	res.l_n_f, res.rating
PUBLISHED_TRANSMISSION_LOSS	mapping	Two hundred and fifty-five measured constructions from ten published tables, keyed '<table>/<row>'. • Bies 5e Table 7.6, nine groups from sheet panels and sandwich panels through masonry, stud partitions, glazing and doors to floors • ASHRAE Chapter 49 Table 40, nine machine equipment room walls, floors and ceilings with the Sound Transmission Class the page prints beside each one • Rossing (2014) Table 11.4, twenty-three common partitions in six bands with an STC • Harris 3e Tables 31.2, 31.3 and 31.5 to 31.9, a hundred and twenty-nine STC ratings with no band: stud walls, block walls, doors, sealed windows and floor-ceiling systems, one row per condition the page rates, the condition in variant • each row carries the thickness_mm and the surface_density_kg_m2 the page prints beside the description, which is what tells apart six windows all called "Single glass in heavy frame" • the book calls the values representative, says they come from tests published by manufacturers and laboratories, and names no standard, no mounting and no source per row; the qualifier it does give is field incidence • what a formula does not give you: the same 280 mm brick wall is 40 dB at 500 Hz on strip ties and 55 dB on expanded metal ties • the transcription was made twice, from the rendered pages, by readers who never saw each other's work	row = building.PUBLISHED_TRANSMISSION_LOSS['bies-2017-table-7-6/6_mm_steel_plate_6mm'] row.spectrum()[500] # 41 dB • TransmissionLossSpectrum, transmission_loss_named
TransmissionLossSpectrum	dataclass	One construction of a published table, with its transmission loss in each octave band. • transmission_loss_63_db … transmission_loss_8000_db, in decibels, None where the page prints a dash • thickness_mm, surface_density_kg_m2: the two columns Bies prints beside the description; two rows carry no weight and say so • sound_transmission_class: the single-number rating a page prints where it prints one, kept because an STC is computed from third octaves and these seven or eight bands do not give it back; seven tables print nothing else • block_mass_kg: the mass of one masonry block where a page prints it, which is not a surface density • refers_to_row: the row a printed "Igual que 8" inherits from; resolve with PUBLISHED_TRANSMISSION_LOSS[f'{row.table}/{row.refers_to_row}'] • .bands(), .spectrum() → {band_hz: db}, .transmission_loss_db(band_hz) narrows or refuses, naming the row and the band • a measurement of one construction in one laboratory, not a property of a material	row.transmission_loss_db(63) # ValueError: the page prints a dash there • PUBLISHED_TRANSMISSION_LOSS
TRANSMISSION_LOSS_BANDS_HZ	constant	The octave bands a published transmission loss table can print: 63 Hz to 8 kHz. • (63, 125, 250, 500, 1000, 2000, 4000, 8000); Bies fills the six middle bands on every row and leaves the ends empty on about forty	building.TRANSMISSION_LOSS_BANDS_HZ
transmission_loss_named	function	Every published construction whose printed description contains a fragment. • name: matched without case against the description the page prints, and nothing else • 'door' answers with the rows that carry the word, not with Bies's hollow flush panel described without it, nor with the Spanish 'puerta' of Harris	[r.thickness_mm for r in building.transmission_loss_named('Concrete, reinforced')] # [100, 200, 300] • PUBLISHED_TRANSMISSION_LOSS
PUBLISHED_IMPACT_INSULATION	mapping	Seventy-one rows of measured impact insulation, keyed '<table>/<row>'. • Harris 3e Tables 32.1 to 32.8: forty-two floor-ceiling constructions with their IIC, and six elastic surface treatments with the improvement each adds over a hard massive floor • Harris (1977) Tables 19.2 to 19.4: twenty-three floor finishes, floating screeds and timber floors on bare concrete, with the average improvement in impact sound insulation in decibels, keyed by a slug of the description • Tables 32.1 to 32.7 are keyed by the row number the page prints in its own column, '1' to '38', with a lettered pair such as '34A'/'34B' where a construction is printed as two rows, each with its own description and rating; the six treatments of Table 32.8 and every 1977 row are keyed by a slug of the description • single numbers and nothing per band: these pages print no impact sound pressure level, no octave, no third octave and no reference curve • Chapter 32 is collected measurements from a 1967 report for the Federal Housing Administration, except Table 32.8, which credits a 1963 paper by Zeller; the 1977 tables credit nothing; no laboratory, no test standard and no uncertainty is named for any row • what a formula does not give you: the same reinforced concrete slab is IIC 25 bare and 80 under a wool carpet on a rubber underlay	row = building.PUBLISHED_IMPACT_INSULATION['harris-1995-tables-32-1-to-32-8/4'] row.impact_insulation_class # 80 • ImpactInsulation, impact_insulation_named
ImpactInsulation	dataclass	One floor-ceiling construction, or one surface treatment, as its page prints it. • impact_insulation_class: the IIC of a whole assembly, dimensionless, from Tables 32.1 to 32.7 • impact_insulation_class_improvement: the delta-IIC a treatment adds, from Table 32.8 alone; no row carries both, because a difference between two ratings is not a rating • impact_sound_improvement_db: the 1977 edition's average improvement in impact sound insulation, in decibels, a level difference and neither of the two above; added_load_pa is the load a floor of Table 19.4 was measured under, printed in kg/cm² and held in pascals • refers_to_row: twelve descriptions are printed in full and refer to another row rather than repeating the structural floor; resolve with PUBLISHED_IMPACT_INSULATION[f'{row.table}/{row.refers_to_row}'] • has_section_drawing: the "Esquema" cell is a drawing with no textual equivalent, so that is all the row records of it • layer_density_kg_m3: a mass density the running description buries, on the three rows that print one; it is one layer's, which is why it says layer, and row 35A serves none because the page prints that cell twice and the two printings disagree • misprinted: seventeen rows carry a pair whose two halves are not each other, registered in docs/ERRATA.md; the printed description is kept whole beside the mark • attributed_to: every row of Chapter 32 names the credit of its own table, because Tables 32.1 to 32.7 are a 1967 NBS survey and Table 32.8 a 1963 paper by Zeller; the 1977 rows credit nothing	row.why_missing('impact_insulation_class') # the page does not give it
impact_insulation_named	function	Every published row whose printed description contains a fragment. • name: matched without case against the description, which is the only thing these tables name a construction by • the descriptions are in the language of the page, and a fragment crosses the two tables: 'linóleo' answers with four floors that carry a linoleum finish and the five treatments of Table 32.8	building.impact_insulation_named('baldosa de vinilo') # one row • PUBLISHED_IMPACT_INSULATION
mass_law_transmission_loss / field_incidence_correction	function	Panel mass law TL (Bies Eq. 7.40/7.42). • frequency [Hz], mass_per_area m'' [kg/m²] • incidence: 'normal'/'field', band: 'third' (−5.5 dB) / 'octave' (−4.0 dB), or field_correction [dB] (Norton uses a flat 5 dB) • +6 dB/octave and +6 dB/mass doubling	tl = building.mass_law_transmission_loss(500, 20)
single_panel_transmission_loss	function	Single-panel R, Sharp's method (Bies 7.2.4.1). • frequency [Hz], mass_per_area [kg/m²] • critical_frequency fc [Hz] or bending_stiffness B' [N·m] • loss_factor η, band, coincidence_model: 'sharp' (Bies 7.44) / 'cremer' (Norton 3.110)	r = building.single_panel_transmission_loss(f, 15, critical_frequency=2100) • SoundReductionResult
plateau_transmission_loss / PLATEAU_MATERIALS	function / mapping	Plateau (Watters) TL estimate (Norton & Karczub 3.9.1, Table 3.1). • frequency [Hz]; material + thickness_mm, or mass_per_area + plateau_height + frequency_ratio • field-incidence mass law → horizontal coincidence plateau (point A to B) → 10 dB/octave • PLATEAU_MATERIALS: 8 materials as (kg/m² per mm, plateau dB, B/A)	r = building.plateau_transmission_loss(f, material='brick', thickness_mm=110) • SoundReductionResult with plateau_height, plateau_start, plateau_end
orthotropic_transmission_loss	function	Orthotropic (ribbed / corrugated) panel R (Vigran 6.5.3; Bies 7.2.4.5). • frequency [Hz], mass_per_area m'' [kg/m²] • critical_frequency_lower fc1 / critical_frequency_upper fc2 [Hz] • method: 'integral' (Vigran Eq. 6.111 double integral, uses loss_factor η) / 'heckl' (Bies Fig. 7.9b design chart, needs fc2 > 4·fc1) • area S [m²] (Bies Eq. 7.36 limit) or limiting_angle_deg θL [deg] (Default: 78)	r = building.orthotropic_transmission_loss(f, 7.5, critical_frequency_lower=400, critical_frequency_upper=4000) • SoundReductionResult with critical_frequency_upper
orthotropic_critical_frequencies	function	Coincidence range (fc1, fc2) of an orthotropic panel (Vigran Eq. 6.107). • mass_per_area m'' [kg/m²] • bending_stiffness_1 / bending_stiffness_2 [N·m] (order irrelevant) • speed_of_sound (Default: 343.0) • the stiffest direction gives the lowest fc	fc1, fc2 = building.orthotropic_critical_frequencies(8.5, 17.5, 2202) • (float, float) [Hz], sorted
corrugated_plate_stiffness / corrugated_plate_mass_factor	function	Equivalent stiffnesses and developed length of a sinusoidal corrugation (Vigran Eq. 3.115, Timoshenko & Woinowsky-Krieger). • thickness h, corrugation_amplitude H, corrugation_wavelength L [m] • youngs_modulus E [Pa], poisson_ratio ν (Default: 0.3) • the mass factor is the arc length of one period over the period	bx, bz, bxz = building.corrugated_plate_stiffness(1e-3, 0.01, 0.1, youngs_modulus=2.1e11) m = 7.8 * building.corrugated_plate_mass_factor(0.01, 0.1) • (Bx, Bz, Bxz) [N·m]; factor ≥ 1
orthotropic_plate_resonance	function	Eigenfrequency of a simply supported orthotropic plate (Vigran Eq. 3.113 = Bies Eq. 7.27, Hearmon 1959). • mode_x i, mode_z n (≥ 1) • length_x a, length_z b [m], mass_per_area m'' [kg/m²] • bending_stiffness_x / _z / _xz [N·m] • the panel TL models are valid above ≈ 1.5·f₁,₁	orthotropic_plate_resonance(1, 1, length_x=1.0, length_z=1.0, mass_per_area=7.8, bending_stiffness_x=b, bending_stiffness_z=b, bending_stiffness_xz=b) • [Hz]
double_wall_transmission_loss / mass_spring_mass_resonance	function	Double-wall R (Bies 7.2.6, Eq. 7.62-7.64). • mass1/mass2 [kg/m²], gap d [m] • cavity_medium: porous fill (PorousMediumResult) lowers f0 • below f0 = total-mass law; f0 = mass-air-mass resonance	r = building.double_wall_transmission_loss(f, 12, 12, 0.1) • SoundReductionResult
heavy_impact_source_specification / heavy_impact_source_limits / HeavyImpactSourceSpec / HEAVY_IMPACT_SOURCES / HEAVY_IMPACT_OCTAVE_BANDS	function / dataclass / mapping / tuple	Standard heavy and soft impact source (ISO 16283-2 Table A.1, JIS A 1418-2 Tables A.1/A.2). • source: 'rubber_ball' / 'bang_machine' • printed LFE per octave 31.5-500 Hz with tolerance, drop height, effective mass, restitution, 20 ± 2 ms contact time	spec = building.heavy_impact_source_specification('rubber_ball') f, lo, hi = building.heavy_impact_source_limits('bang_machine')
check_heavy_impact_source / HeavyImpactSourceCheck	function / dataclass	Source conformance against the printed spectrum. • force_exposure_level: five octave-band LFE [dB re 1 N] • source: 'rubber_ball' / 'bang_machine' • .plot()	chk = building.check_heavy_impact_source([39, 31, 23, 17, 12.5]) • HeavyImpactSourceCheck (passes, deviation, within_tolerance)
impact_force_exposure_level	function	Impact force exposure level LFE (ISO 16283-2 Formula (A.1)). • force F(t) [N] (1-D record of one impact), fs [Hz] • reference_force F0 (Default: 1 N), reference_time Tref (Default: 1 s)	lfe = building.impact_force_exposure_level(force, 200_000) • [dB re 1 N]
standardized_maximum_impact_level / fast_reverberation_correction / StandardizedMaximumImpactResult	function / dataclass	Standardized maximum impact level L'i,Fmax,V,T (ISO 16283-2 Formulae (4)-(6)). • level Li,Fmax [dB], volume V [m³], reverberation_time T [s] • reference_time T0 (Default: 0.5 s), reference_volume V0 (Default: 50 m³) • the Fast correction is exactly 0 dB at T = T0 • .plot()	res = building.standardized_maximum_impact_level(li, 41.4, t) • StandardizedMaximumImpactResult
heavy_impact_octave_levels	function	One-third-octave to octave synthesis (ISO 16283-2 Formula (20)). • level: thirds in ascending order, length a multiple of 3	oct = building.heavy_impact_octave_levels(thirds) • [dB]
a_weighted_maximum_impact_level / HEAVY_IMPACT_A_WEIGHTING / AWeightedMaximumImpactResult	function / mapping / dataclass	A-weighted maximum impact level XiA,Fmax (ISO 717-2 Annex D, Formula (D.1)). • level: 12 thirds (50-630 Hz) or 4 octaves (63-500 Hz) [dB] • band: 'third' / 'octave' (inferred from the length) • Table D.3 corrections, rounded half-up • .plot()	res = building.a_weighted_maximum_impact_level([65.3, 64.5, 58.0, 55.8]) • AWeightedMaximumImpactResult (rating = 55 dB)
normalized_ceiling_attenuation	function	Normalized ceiling attenuation Dn,c (ISO 140-9 clause 3.3). • level_source L1, level_receiving L2 [dB], absorption_area A [m²] • reference_area A0 (Default: 10 m² ISO; ASTM E1414 uses 12 m²)	dnc = building.normalized_ceiling_attenuation(l1, l2, a)
ceiling_attenuation_class / CEILING_ATTENUATION_CONTOUR / CeilingAttenuationResult	function / mapping / dataclass	Ceiling attenuation class CAC (ASTM E413-22 clause 5, via ASTM E1414). • attenuation Dn,c: 16 thirds 125-4000 Hz [dB] • data rounded to integers (5.2), Σ deficiencies ≤ 32 dB, max ≤ 8 dB • .plot()	res = building.ceiling_attenuation_class(dnc) • CeilingAttenuationResult (rating, deficiencies)
plenum_flanking_reduction_index / partition_referenced_reduction_index / PlenumFlankingResult	function / dataclass	Suspended-ceiling plenum flanking path Rcl (Vigran Eqs. (9.13), (9.18)-(9.20)). • reduction_index_source RS / _receiving RR [dB] • ceiling_length LR, plenum_height h [m] • sidewalls: 'reflecting' (ε = 2) / 'absorbing' (ε = 1) • attenuation_source / _receiving m [1/m] switch to Eq. (9.18) • .plot()	res = building.plenum_flanking_reduction_index(rs, rr, ceiling_length=4.75, plenum_height=0.43) • PlenumFlankingResult
wall_tie_stiffness / wall_tie_stiffness_per_area / WALL_TIE_STIFFNESS	function / mapping	Dynamic stiffness of masonry wall ties (Hopkins Table A4). • tie: 'butterfly' (1.7 MN/m) / 'double_triangle' (16.1) / 'vertical_twist' (94.0) at 50 mm, 'vertical_twist_100mm' (43.4) • ties_per_area n [1/m²] → N·k/S [N/m³] for tie_stiffness_per_area	s = building.wall_tie_stiffness_per_area(2.5, 'vertical_twist_100mm') • feeds mass_spring_mass_resonance / double_wall_transmission_loss
wall_tie_coupling_loss_factor / WallTieCouplingResult	function / dataclass	Structure-borne coupling of a tie array (Hopkins Eqs. 4.87/4.88). • frequency [Hz], mass1/mass2 [kg/m²], bending_stiffness1/2 [N·m] • ties_per_area n [1/m²], tie: name, k [N/m], or None (rigid, Yc = 0) • .plot()	res = building.wall_tie_coupling_loss_factor(f, 150, 170, b1, b2, ties_per_area=2.5, tie='butterfly') • WallTieCouplingResult
plot_double_wall_geometry	function	Mass-spring-mass cross-section to scale. • mass1, mass2 [kg/m²], gap [m] • resonance_frequency [Hz] (annotation) • language	plot_double_wall_geometry(8.8, 8.8, 0.1) • Also SoundReductionResult.plot_geometry() (double-wall results)
SoundReductionResult	dataclass	Predicted R(f) of a construction (Bies 7.2). • transmission_loss R [dB], transmission_coefficient τ • critical_frequency / critical_frequency_upper (orthotropic fc1/fc2) / resonance_frequency • .rating() → Rw (ISO 717-1), .plot()	res.transmission_loss, res.rating().rating
slit_transmission_coefficient / slit_resonance_frequencies	function	Straight slit τ (Hopkins Eq. 4.99, Gomperts). • frequency [Hz], width w [m], depth d [m] • field: 'diffuse'/'normal', position: 'mid'/'edge' • maxima at d+2e = zλ/2	res = building.slit_transmission_coefficient(f, 0.002, 0.1) • ApertureTransmissionResult
circular_aperture_transmission_coefficient	function	Circular hole τ (Hopkins Eq. 4.102, Wilson-Soroka). • frequency [Hz], radius a [m], depth d [m] • τ → 1 for a large hole	res = building.circular_aperture_transmission_coefficient(f, 0.01, 0.002) • ApertureTransmissionResult
plot_aperture_geometry	function	Wall-aperture section to scale. • depth d [m] • Exactly one of width w / radius [m] • language	plot_aperture_geometry(0.1, width=0.003) • Also ApertureTransmissionResult.plot_geometry()
composite_transmission_loss / transmission_loss_from_coefficient	function	Composite R of parallel elements (Hopkins Eq. 4.92). • areas Sₙ [m²], reduction_indices Rₙ [dB] (1-D or (N, bands)) • a bare opening (Sₐ/S) caps R at 10 lg(S/Sₐ)	r = building.composite_transmission_loss([0.99, 0.01], [55, 0])
ApertureTransmissionResult	dataclass	Slit / hole transmission (Hopkins 4.3.10). • transmission_coefficient τ, transmission_loss R = −10 lg(τ) • kind: 'slit'/'circular', .plot()	res.transmission_loss
band_uncertainty	function	One-third-octave standard uncertainty u (ISO 12999-1 Tables 2/4/6). • measurand: 'airborne'/'impact'/'impact_reduction' • situation: 'A'/'B'/'C' • upper_limit: σR95 (airborne A, Annex D) (Default: False)	u = building.band_uncertainty('airborne', 'B') • BandUncertainty
single_number_uncertainty	function	Single-number standard uncertainty u (ISO 12999-1 Tables 3/5/7). • quantity: 'r_w'/'ln_w'/'delta_lw' (+ aliases, +c/+ctr variants) • situation: 'A'/'B'/'C' • upper_limit (Default: False)	u = building.single_number_uncertainty('r_w', 'B') • u [dB] (0.9)
single_number_uncertainty_uncorrelated	function	Uncorrelated single-number u from bands (ISO 12999-1 Formula B.2). • band_uncertainties: per-band u_i [dB] • reference_differences: L_i − R_i [dB]	u = building.single_number_uncertainty_uncorrelated(u_i, d_i) • Energy-weighted quadrature u [dB]
maximum_repeatability_standard_deviation	function	Max repeatability σx per band (ISO 12999-1 Table 1). • (no parameters)	b = building.maximum_repeatability_standard_deviation() • BandUncertainty (lab self-verification)
insulation_coverage_factor	function	Coverage factor k (ISO 12999-1 Table 8). • confidence: fraction (Default: 0.95) • one_sided (Default: False)	k = building.insulation_coverage_factor(0.95) • 1.96 (two-sided) / 1.65 (one-sided)
insulation_expanded_uncertainty	function	Expanded uncertainty U = k·u (ISO 12999-1 Formula 2). • u [dB] • coverage: fraction (Default: 0.95) • one_sided (Default: False); enforces k ≥ 1	U = building.insulation_expanded_uncertainty(0.9) • 1.764 [dB]
uncertain_value	function	Attach U to a rating (ISO 12999-1 Clause 8). • value [dB], quantity, situation • coverage (Default: 0.95), one_sided (Default: False), upper_limit (Default: False)	uv = building.uncertain_value(52.0, 'rprime_w', 'B') • UncertainValue (value ± U)
combine_uncertainties	function	Quadrature combination (ISO 12999-1 Formula C.2). • *components: non-negative u_i [dB]	uc = building.combine_uncertainties(1.0, 0.6) • sqrt(Σ u_i²) = 1.166 [dB]
prediction_input_uncertainty	function	Prediction input uncertainty (ISO 12999-1 Formula A.1). • sigma_reproducibility, sigma_product [dB] • n: measurements (≥ 1)	u = building.prediction_input_uncertainty(1.8, 1.0, 3) • sqrt((σR²+σp²)/n + σp²) [dB]
reduce_by_independent_measurements	function	Reduce u by m measurements (ISO 12999-1 Formula A.7). • u [dB] • m: independent measurements (≥ 1)	ur = building.reduce_by_independent_measurements(1.0, 4) • u/√m = 0.5 [dB]
satisfies_lower_requirement	function	Conformity to a minimum (ISO 12999-1 Formula 5). • value, expanded_uncertainty_value, requirement [dB]	ok = building.satisfies_lower_requirement(52.0, 1.485, 50.0) • True when value − U > requirement
satisfies_upper_requirement	function	Conformity to a maximum (ISO 12999-1 Formula 4). • value, expanded_uncertainty_value, requirement [dB]	ok = building.satisfies_upper_requirement(45.0, 1.5, 50.0) • True when value + U < requirement
BandUncertainty	dataclass	Per-band standard uncertainty (ISO 12999-1). • measurand, situation • frequencies [Hz], uncertainties [dB] • upper_limit: σR95 flag • .to_arrays()	b.frequencies, b.uncertainties
UncertainValue	dataclass	A value with its expanded uncertainty. • value, standard_uncertainty, expanded_uncertainty [dB] • coverage_factor, confidence, one_sided • .lower = y − U, .upper = y + U	uv.lower, uv.upper
COVERAGE_FACTORS	mapping	Table 8 coverage factors (read-only). Keyed by (confidence, one_sided) → k	COVERAGE_FACTORS[(0.95, False)] # 1.96
sound_absorption_coefficient_uncertainty	function	Absorption-coefficient uncertainty αs (ISO 12999-2 Table 1, Formula 1). • alpha, frequencies [Hz] (1/3-oct 63–5000) • condition: 'reproducibility'/'repeatability' • confidence (Default: 0.95)	r = materials.sound_absorption_coefficient_uncertainty(a_s, f) • AbsorptionUncertaintyResult
equivalent_area_uncertainty	function	Equivalent-area uncertainty AT (ISO 12999-2 Formula 2, S = 10 m²). • area, frequencies [Hz] • condition, confidence (Default: 0.95)	r = materials.equivalent_area_uncertainty(a_t, f) • AbsorptionUncertaintyResult
practical_coefficient_uncertainty	function	Practical-coefficient uncertainty αp (ISO 12999-2 Table 2, Formula 4). • alpha_p, frequencies [Hz] (octave 250–4000) • condition, confidence (Default: 0.95)	r = materials.practical_coefficient_uncertainty(a_p, f) • AbsorptionUncertaintyResult
weighted_coefficient_uncertainty	function	Weighted-coefficient uncertainty αw (ISO 12999-2 Formulae 6/7). • alpha_w (carried for the interval) • condition, confidence	weighted_coefficient_uncertainty(0.70) • σR = 0.035 / σr = 0.020
single_number_rating_uncertainty	function	DLα,NRD uncertainty (ISO 12999-2 Formulae 8/9, EN 1793-1). • dl_alpha [dB] (≥ 0) • condition, confidence	single_number_rating_uncertainty(8.1) • σR = 0.10·DLα / σr = 0.02·DLα
absorption_coverage_factor	function	Coverage factor k (ISO 12999-2 Table 3, rounded). • confidence: 0.68/0.80/0.90/0.95/0.99/0.999	absorption_coverage_factor(0.95) # 2.0
AbsorptionUncertaintyResult	dataclass	Absorption uncertainty (ISO 12999-2). • standard_uncertainty u, expanded_uncertainty U = k·u • reported_expanded_uncertainty (Clause 8 rounding) • .lower, .upper, .plot()	r.reported_expanded_uncertainty
sound_power_pressure	function	Sound power from surface pressure (ISO 3744/3746). • levels_positions: (NM, NB) SPL [dB] • surface: 'hemisphere' / 'box' • radius [m] or dimensions+distance [m] • reflecting_planes: 1/2/3 (Default: 1) • background_levels: for K1 • frequencies [Hz]: for LWA • room: RoomEnvironment for K2 (Default: None → free field) • grade: 'engineering' (Default) / 'survey' • omc_uncertainty [dB] (Default: 0)	res = emission.sound_power_pressure(levels, 'hemisphere', radius=1.5, frequencies=f) • SoundPowerResult
measurement_positions	function	Hemisphere mic coordinates (ISO 3744 Annex B). • surface: 'hemisphere' • radius [m] • reflecting_planes: 1/2/3 • tones: Table B.1 vs B.2 (Default: True) • grade: 'engineering'/'survey'	xyz = emission.measurement_positions('hemisphere', radius=1.5) • (N, 3) coordinates [m]
plot_microphone_positions	function	3-D microphone array on its measurement surface. • positions: (N, 3) [m] from measurement_positions/precision_positions • radius [m] (Default: largest norm) • language	plot_microphone_positions(emission.measurement_positions('hemisphere', radius=2.0), radius=2.0) • Numbered points + hemisphere/sphere wireframe + reflecting plane
emission_sound_pressure_level	function	L_p at a work station: the reading less both corrections (ISO 11201 Eq. 7, ISO 11202 Eq. 10, ISO 11204 Eq. 9). • measured_level_db [dB] • background_correction_db K1 [dB], local_correction_db K3 [dB] Never for a peak level: neither correction is permitted on one	emission.emission_sound_pressure_level(76.9, local_correction_db=3.7) # 73.2
background_noise_correction_at_workstation	function	K1 with the ISO 11200 group's own thresholds. • measured_level_db, background_level_db [dB] • grade: 'engineering' (6 dB floor) / 'survey' (3 dB) Past 15 dB of margin K1 is zero; below the floor it is held there and the level becomes an upper bound	k1, held = emission.background_noise_correction_at_workstation(79.0, 70.0)
local_environmental_correction	function	K3, the piecewise correction of ISO 11202 Eq. (A.5) and ISO 11204 Eqs. (A.2)/(A.5). • ratio: the dimensionless z 7 dB for z ≤ 0,2, −10 lg z up to 1, then 0; continuous where the cap takes over	emission.local_environmental_correction(0.5) # 3.01
environmental_ratio_from_k2	function	z from the environmental correction of the test room (ISO 11202 Eq. A.4, ISO 11204 Eq. A.3). • environmental_correction_db K2 [dB] • directivity_index_db [dB] (Default: 0) With no directivity K3 comes out equal to K2	emission.environmental_ratio_from_k2(3.73)
environmental_ratio_from_absorption	function	The same z from the equivalent absorption area (ISO 11204 Eq. A.6). • absorption_area_m2 A, measurement_surface_m2 S_M • directivity_index_db [dB] (Default: 0) Identically equal to the K2 route under the ISO 3744 definition of K2	emission.environmental_ratio_from_absorption(47.0, 16.0)
grade_from_local_correction	function	The accuracy grade K3 earns (ISO 11202 A.1.3). • local_correction_db [dB]; the worst band decides 4 dB or less is grade 2, more is grade 3	emission.grade_from_local_correction(3.7) # 'engineering'
operating_standard_deviation	function	sigma_omc of repeated readings, Equation (C.1). • levels_db: at least two readings [dB] Sample standard deviation, 1/(N−1), as printed; see docs/ERRATA.md on the two Annex B tables	emission.operating_standard_deviation([79.0, 80.2, 82.9]) # 2.0
total_standard_deviation	function	sigma_tot = sqrt(sigma_R0² + sigma_omc²). • reproducibility_db of the method, operating_db of the machine [dB]	emission.total_standard_deviation(1.5, 1.0) # 1.80
emission_expanded_uncertainty	function	U = k·sigma_tot for the ISO 11200 group. • total_standard_deviation_db [dB] • coverage_factor (Default: 1.6, what the worked examples print)	emission.emission_expanded_uncertainty(1.8) # 2.88
subinterval_level	function	One level for a cycle of operating periods of different lengths. • levels_db, durations_s Energy average weighted by duration, not by count	emission.subinterval_level([80.0, 90.0], [10.0, 1.0])
EmissionPressureResult	dataclass	An emission sound pressure level and the two corrections behind it. • level_db, measured_level_db, background_correction_db, local_correction_db • grade, upper_bound, standard • .plot(): the reading, both corrections and what is left, as a waterfall	res.level_db, res.upper_bound
NEGLIGIBLE_BACKGROUND_MARGIN_DB / MINIMUM_BACKGROUND_MARGIN_DB	constant / mapping	The two background thresholds of the group: 15 dB above which K1 is zero, and the 6 dB (grade 2) / 3 dB (grade 3) floor a determination may be claimed from.	emission.MINIMUM_BACKGROUND_MARGIN_DB['engineering'] # 6.0
MAX_K3_DB / GRADE_2_MAX_K3_DB	constant	The 7 dB cap on K3, and the 4 dB above which the result is grade 3 rather than grade 2.	emission.GRADE_2_MAX_K3_DB # 4.0
DEFAULT_COVERAGE_FACTOR	constant	k = 1,6, the factor the ISO 11200 group's worked examples print.	emission.DEFAULT_COVERAGE_FACTOR # 1.6
background_noise_correction	function	Background correction K1 (ISO 3744 Eq. 16). • source_levels [dB] • background_levels [dB] • grade: 'engineering'/'survey'	k1 = emission.background_noise_correction(src, bg) • K1 per band [dB]
environmental_correction	function	Environmental correction K2 (ISO 3744 Eq. A.2). • surface_area S [m²] • absorption_area A, or reverberation_time+volume, or mean_absorption_coefficient+room_surface	k2 = emission.environmental_correction(14.1, reverberation_time=0.6, volume=300) • K2 [dB]
SoundPowerResult	dataclass	Surface-pressure sound power. • sound_power_level [dB] • surface_pressure_level, mean_pressure_level [dB] • background_correction, environmental_correction [dB] • directivity_index [dB] (NM, NB) • surface_area [m²] • sound_power_level_a [dB] • uncertainty [dB] • grade • declare(...) → NoiseEmissionDeclaration	res.sound_power_level, res.sound_power_level_a
RoomEnvironment	dataclass	Room data behind K2 (ISO 3744 Annex A), for sound_power_pressure. • absorption_area A [m²] • reverberation_time T [s] + volume V [m³] (Eq. A.3) • mean_absorption_coefficient α + room_surface Sv [m²] (Eq. A.7) All Default: None; the empty environment is a free field (K2 = 0)	RoomEnvironment(reverberation_time=0.6, volume=300)
sound_energy_pressure	function	Sound energy level LJ of a burst from surface single event levels (ISO 3744 8.3 / ISO 3746 8.4). • levels_positions: (NM, NB) single event levels, or (Ne, NM, NB) per event [dB] • surface, radius / dimensions+distance, reflecting_planes: as sound_power_pressure • events: Ne encompassed by one reading (Eq. 20) • background_levels [dB] + integration_time T [s] (required together): K1 over the same window • frequencies [Hz]: for LJA • room: RoomEnvironment for K2 • grade, omc_uncertainty	lj = emission.sound_energy_pressure(events, 'hemisphere', radius=2.0, frequencies=f) • SoundEnergyResult
SoundEnergyResult	dataclass	Surface single-event sound energy. • frequencies [Hz] (or None) • sound_energy_level [dB re 1 pJ] • surface_event_level, mean_event_level [dB] • background_correction, environmental_correction [dB] • directivity_index (NM, NB) • surface_area [m²] • sound_energy_level_a [dB] • uncertainty [dB], grade • events (a count) • integration_time [s]	lj.sound_energy_level, lj.sound_energy_level_a
mean_single_event_level	function	Level of one event from Ne events (ISO 3744 Eq. 19/20). • levels: per-event levels on the first axis (Eq. 19), or one reading of events events (Eq. 20) [dB] • events: Ne of one reading (Default: None)	emission.mean_single_event_level(per_event) emission.mean_single_event_level(reading, events=5)
reference_atmosphere_correction	function	Annex G corrections C1, C2 to 101.325 kPa and 23 °C (ISO 3744 Eq. G.1/G.3). • temperature_c [°C] • static_pressure_kpa [kPa], or altitude [m] via Eq. G.2	corr = emission.reference_atmosphere_correction(8.0, altitude=1200.0) • ReferenceAtmosphereCorrection
ReferenceAtmosphereCorrection	dataclass	The two Annex G corrections. • c1, c2, total [dB] • static_pressure_kpa [kPa], temperature_c [°C]	lj_ref = lj.sound_energy_level + corr.total
OperatingModeDeclaration	dataclass	ISO 4871 dual-number values for one operating mode. • mode: column label • sound_power_level L_WA [dB re 1 pW] • sound_power_uncertainty K_WA [dB] • emission_pressure_level L_pA, emission_pressure_uncertainty K_pA [dB] (optional) • verification_level L_1 [dB] (optional) • declared_sound_power_level: L_WAd = L_WA + K_WA (3.15) • verified: L_1 ≤ L_WAd (6.2, combined form) • verified_dual: L_1 ≤ round(L_WA) + round(K_WA) (6.2, dual-number form)	OperatingModeDeclaration('Mode 1', 88.0, 2.0)
DeclarationForm	constant	The form literal of NoiseEmissionDeclaration (ISO 4871 clause 6). • 'dual-number': L_WA and K_WA declared as a pair (Default) • 'single-number': the declared L_WAd alone	NoiseEmissionDeclaration(modes, form='single-number')
NoiseEmissionDeclaration	dataclass	ISO 4871:1996 noise emission declaration (machinery). • modes: OperatingModeDeclaration per mode • machine, operating_conditions (clause 5) • noise_test_code, basic_standards (clause 5 b) • form: 'dual-number' (Default) / 'single-number' • .report(path, ...): ISO 4871 fiche → PDF	NoiseEmissionDeclaration((m1, m2), machine='...').report('iso4871.pdf')
sound_power_reverberation	function	Reverberation-room LW, direct (ISO 3741). • levels: mean room SPL [dB] (1D or (NM, NB)) • t60 [s] • volume V [m³] • surface_area S [m²] • frequencies [Hz] (required) • background_levels: for K1 • temperature_c [°C] (Default: 23) • static_pressure_kpa [kPa] (Default: 101.325)	rev = emission.sound_power_reverberation(lp, t60, 200, 220, f) • ReverberationSoundPowerResult
reverberation_background_correction	function	The background-noise correction K1 of ISO 3741:2010 Eq. (14), on its own. • levels, background_levels, frequencies, all per band [dB, dB, Hz] • K1 = −10 lg(1 − 10^(−0.1 ΔL)), with the qualification of 9.1.2: the lower criterion is 6 dB at 200 Hz and below and at 6.3 kHz and above and 10 dB between them, below it the correction is held there and the answer is an upper bound, and at 15 dB and over there is nothing to correct • the standards that ask for a correction in accordance with ISO 3741, ISO 11957 four times over, call this rather than repeat it	emission.reverberation_background_correction(lp, bg, f) • K1 [dB]
sound_power_comparison	function	Reverberation-room LW, comparison (ISO 3741). • levels, levels_ref: room SPL [dB] • lw_ref: reference-source LW [dB] • frequencies [Hz] • background_levels, background_levels_ref • temperature_c, static_pressure_kpa	cmp = emission.sound_power_comparison(lp, lp_ref, lw_ref) • ReverberationSoundPowerResult (method='comparison')
ReverberationSoundPowerResult	dataclass	Reverberation-room sound power. • frequencies [Hz] (or None) • sound_power_level [dB] • mean_pressure_level [dB] • absorption_area [m²] • waterhouse_correction [dB] • background_correction, c1, c2 [dB] • speed_of_sound [m/s] • sound_power_level_a [dB] • method	rev.sound_power_level, rev.waterhouse_correction
sound_power_in_situ	function	In situ LW by comparison with a reference sound source (ISO 3747). • levels: (n, bands) L'pi(ST) [dB] • levels_ref: (n, bands) or (m, n, bands) L'pi(RSS) [dB] • lw_ref: calibrated LW(RSS) [dB], per band or per location • frequencies [Hz] (octaves 63 Hz–8 kHz, required; 63 Hz only where the environment and instrumentation suit it, Table D.1 footnote a) • background_levels, background_levels_ref: for K1 (8.1 rules) • temperature_c [°C] (Default: 23), static_pressure_kpa [kPa] (Default: 101.325) • conditions: GradeConditions(excess_levels, directivity_range) for the Table 2 grade • sigma_omc [dB], coverage_factor (Default: 2)	res = emission.sound_power_in_situ(lp, lp_ref, lw_ref, f, background_levels=lb) • InSituSoundPowerResult
sound_energy_in_situ	function	In situ LJ of an impulsive source (ISO 3747 clauses 8.4, 8.5). • event_levels: (n, N, bands) events one at a time, or (n, bands) with events=N • integration_time [s]: carries Lp(B) to the event interval (Eq. 14) • the rest as sound_power_in_situ	res = emission.sound_energy_in_situ(le, lp_ref, lw_ref, f, background_levels=lb) • InSituSoundPowerResult (quantity='energy')
GradeConditions	dataclass	The two conditions Table 2 reads for the accuracy grade (ISO 3747). • excess_levels: ΔLfA at each microphone position [dB] (Annex A) • directivity_range: half-width of the A-weighted directivity survey [dB] (7.2) Either one left out leaves the determination at survey grade	emission.GradeConditions(excess_levels=[8.2, 7.6, 8.9, 8.0], directivity_range=4.0)
InSituSoundPowerResult	dataclass	In situ comparison result (ISO 3747). • frequencies [Hz] • sound_power_level / sound_energy_level [dB] (the other NaN) • mean_source_level, mean_reference_level, reference_levels, reference_power_level [dB] • background_correction (n, bands), background_correction_ref (m, n, bands) [dB] • background_requirement_met per band • c2 [dB], grade, sigma_r0, sigma_omc, sigma_tot, expanded_uncertainty, coverage_factor • sound_power_level_a / sound_energy_level_a [dB], quantity • .sound_power_level_ref, .sound_energy_level_ref (Annex C) • .plot()	res.sound_power_level, res.background_requirement_met
excess_sound_pressure_level	function	Excess of sound pressure level over the free field ΔLf (ISO 3747 Eq. A.1). • level Lp(RSS),r [dB], lw_ref LW(RSS) [dB], distance r [m]; broadcast	emission.excess_sound_pressure_level(76.5, 92.5, 3.0) # 4.54 dB
static_pressure_from_altitude	function	Static pressure from the site altitude (ISO 3747 Eq. C.2). • altitude Ha [m]	emission.static_pressure_from_altitude(640.0) # 93.87 kPa
sound_energy_reverberation	function	Reverberation-room LJ of a single event, direct (ISO 3741 9.2.4, Eq. 30). • levels: single event levels, 1D, (NM, NB) or (Ne, NM, NB) [dB] • t60 [s], volume V [m³], surface_area S [m²], frequencies [Hz] • events: Ne of one reading (Eq. 23) • background_levels [dB] + integration_time T [s]: per-position K1i over the same window • temperature_c, static_pressure_kpa	lj = emission.sound_energy_reverberation(slams, t60, 200, 220, f) • ReverberationSoundEnergyResult
sound_energy_comparison	function	Reverberation-room LJ of a single event, comparison (ISO 3741 9.2.5, Eq. 31). • levels: single event levels of the source under test • levels_ref, lw_ref: the steady reference source • frequencies, events, background_levels + integration_time, background_levels_ref • temperature_c, static_pressure_kpa	lj = emission.sound_energy_comparison(slams, lp_ref, lw_ref, frequencies=f) • ReverberationSoundEnergyResult (method='comparison')
ReverberationSoundEnergyResult	dataclass	Reverberation-room sound energy of a single event. • frequencies [Hz] (or None) • sound_energy_level [dB re 1 pJ] • mean_event_level [dB] • absorption_area [m²], waterhouse_correction [dB] • background_correction, c1, c2 [dB] • speed_of_sound [m/s] • sound_energy_level_a [dB] • method, events (a count) • integration_time [s]	lj.sound_energy_level, lj.method
octave_band_levels	function	Octave-band levels from one-third-octave bands (ISO 3741 Annex F, Eq. F.1/F.4). • levels [dB], bands on the last axis • frequencies [Hz]: nominal thirds 50 Hz to 10 kHz, complete triplets per octave	octaves, lj_oct = emission.octave_band_levels(lj.sound_energy_level, f)
sound_power_in_duct	function	In-duct sound power of a fan (ISO 5136). • levels: SPL [dB], (positions, bands) or an averaged (bands,) • frequencies [Hz]: nominal thirds 50 Hz-20 kHz (required) • duct_diameter_m d [m], 0.15-2 • flow_velocity U [m/s], < 0 inlet, > 0 outlet • shield: 'sampling-tube' (Default)/'nose-cone'/'foam-ball' • microphone_correction C1, shield_correction C2 [dB] • temperature_c [°C] (Default: 20), static_pressure_kpa [kPa] (Default: 101.325)	duct = emission.sound_power_in_duct(lp, f, 0.63, 12.0) • InDuctSoundPowerResult
flow_modal_correction	function	Mean-flow and modal correction C3,4 (ISO 5136 Eq. 7 / Eq. 8). • frequencies [Hz]: nominal thirds • flow_velocity U [m/s], signed • duct_diameter_m [m]: selects the Annex A table • shield: sampling tube polynomial (Annex A) or the omni-directional Eq. 8 • speed_of_sound [m/s] (Default: 340, Eq. 8 only)	c34 = emission.flow_modal_correction(f, 15.0, 0.5) • C3,4 per band [dB]
in_duct_reproducibility	function	Reproducibility σR per band (ISO 5136 Table 2 / Table 3). • frequencies [Hz]: nominal thirds 50 Hz-20 kHz • 12.5-20 kHz: the extrapolated Table 3 values	s = emission.in_duct_reproducibility(f) • σR per band [dB]; U95 = 2 σR (clause 9.2)
InDuctSoundPowerResult	dataclass	In-duct sound power. • frequencies [Hz] • sound_power_level [dB], sound_power_level_a [dB] • mean_pressure_level, corrected_pressure_level [dB] • microphone_correction, shield_correction, flow_modal_correction, combined_correction [dB] • reproducibility_standard_deviation, expanded_uncertainty [dB] • information_only_band: > 10 kHz or |U| > 40 m/s • duct_diameter_m, duct_area, characteristic_impedance, speed_of_sound, flow_velocity, shield	duct.sound_power_level, duct.flow_modal_correction
high_frequency_sound_power	function	Sound power in the 16 kHz octave band, direct method (ISO 9295 Formula (6), clauses 6 and 7). • pressure_levels_db: Lp(ST) [dB], (bands,) or (N, bands) averaged by Formula (1) • frequencies_hz [Hz]: one per band, 11.2-22.4 kHz • room_constant_m2 R [m²], scalar or per band • temperature_c [°C] (Default: 23), static_pressure_kpa [kPa] (Default: 101.325): C1 + C2 of ISO 3741 (clause 10.1) • tonal (Default: False)	res = emission.high_frequency_sound_power(lp, frequencies_hz=f, room_constant_m2=r) • HighFrequencySoundPowerResult (method='direct')
high_frequency_sound_power_comparison	function	Sound power in the 16 kHz octave band against a reference sound source (ISO 9295 Formulae (8) and (9)). • pressure_levels_db: Lp(ST) [dB] • frequencies_hz [Hz] • reference_pressure_levels_db: Lp(FAR) [dB] • reference_sound_power_levels_db: LW(FAR) [dB re 1 pW], per band, or per hertz for tones • noise_bandwidth_hz ΔF [Hz]: selects Formula (9); ≤ 112 Hz for an FFT • temperature_c, static_pressure_kpa: C2 of ISO 3741	res = emission.high_frequency_sound_power_comparison(lp, frequencies_hz=f, reference_pressure_levels_db=lp_ref, reference_sound_power_levels_db=lw_ref, noise_bandwidth_hz=12.5)
room_constant_from_reverberation_time	function	Room constant from the measured reverberation time (ISO 9295 Formulae (4), (5)). • reverberation_time_s T [s], scalar or per band • volume_m3 V [m³], surface_area_m2 S [m²]	r = emission.room_constant_from_reverberation_time([0.70, 0.42, 0.26], volume_m3=200.0, surface_area_m2=210.0) • R per band [m²]
room_absorption_coefficient	function	Room absorption coefficient from the reverberation time, Eyring (ISO 9295 Formula (5)). • reverberation_time_s T [s] • volume_m3 V [m³], surface_area_m2 S [m²] • 1 - exp(-0.16 V/(S T))	emission.room_absorption_coefficient(0.42, volume_m3=200.0, surface_area_m2=210.0)
room_constant_from_air_absorption	function	Room constant from the calculated air absorption (ISO 9295 Formula (7)). • frequencies_hz [Hz] • volume_m3 V [m³], surface_area_m2 S [m²] • temperature_c [°C], relative_humidity_percent [%] (required), static_pressure_kpa [kPa] (Default: 101.325) • 8αV/(1 - 8αV/S); warns below 10 kHz, refuses 8αV/S ≥ 1	r = emission.room_constant_from_air_absorption(f, volume_m3=200.0, surface_area_m2=210.0, temperature_c=23.0, relative_humidity_percent=50.0)
air_absorption_np_per_m	function	Air absorption coefficient α in nepers per metre (ISO 9295 Annex A). • frequencies_hz [Hz], 50 Hz-22.4 kHz without advisory • temperature_c [°C], relative_humidity_percent [%] (required), static_pressure_kpa [kPa] (Default: 101.325) • ISO 9613-1 without the 8.686	emission.air_absorption_np_per_m(16000.0, temperature_c=23.0, relative_humidity_percent=50.0) # 0.0383 Np/m
minimum_analyzer_bandwidth_hz	function	Narrowest analyser bandwidth for a tone under a moving microphone (ISO 9295 Formula (2)). • tone_frequency_hz f [Hz] • microphone_speed_m_s v [m/s], speed_of_sound c [m/s] • Δf = 2 f v / c	emission.minimum_analyzer_bandwidth_hz(15625.0, microphone_speed_m_s=0.196, speed_of_sound=345.5)
tone_level_from_sidebands	function	Total level of a tone from its sidebands (ISO 9295 Formula (3)). • sideband_levels_db [dB re 20 µPa] • the energy sum	emission.tone_level_from_sidebands([42.9, 41.3, 38.0]) # 45.9 dB
free_field_absorption_correction	function	Air absorption correction K_α = r α of the free-field method (ISO 9295 Formula (10)). • frequencies_hz [Hz] • radius_m r [m]: zero at 2 m or less (clause 9.8) • temperature_c [°C], relative_humidity_percent [%], static_pressure_kpa [kPa] (Default: 101.325)	k = emission.free_field_absorption_correction(f, radius_m=2.5, temperature_c=23.0, relative_humidity_percent=50.0)
high_frequency_levels_to_determine	function	The sound power levels to determine for a type of noise (ISO 9295 Table 3). • noise_125_hz_to_8_khz: 'broadband', 'narrowband' or 'none' • noise_16_khz_octave: 'none', 'broadband', 'discrete_tone' or 'multiple_tones' • returns a tuple of 'a_weighted_sound_power_level', 'one_third_octave_band_levels', 'tone_level_and_frequency', 'tone_levels_within_10_db' • ValueError for the two combinations the table has no row for	emission.high_frequency_levels_to_determine(noise_125_hz_to_8_khz='broadband', noise_16_khz_octave='multiple_tones')
HighFrequencySoundPowerResult	dataclass	Sound power in the 16 kHz octave band (ISO 9295). • frequencies [Hz] • sound_power_level [dB re 1 pW], at the reference meteorological conditions • mean_pressure_level [dB] • room_constant [m²] (direct) or reference_sound_power_level, reference_pressure_level [dB] (comparison) • noise_bandwidth_hz, c1, c2 [dB], method, tonal • within_10_db_of_maximum: the tones clause 13 c) reports • .plot()	res.sound_power_level, res.within_10_db_of_maximum res.plot()
sound_power_intensity	function	Sound power by intensity scanning (ISO 9614-2). • normal_intensity: (N_seg, N_bands) [W/m²] • areas: segment Si [m²] • normal_intensity_2: 2nd sweep (criterion 3) • pressure_levels: for FpI • pressure_residual_index: δpI0 [dB] • frequencies [Hz] • band_type: 'third' (Default)/'octave' • grade: 'engineering'/'survey' • repeatability_limit: override s	ir = emission.sound_power_intensity(scan1, areas, frequencies=f, band_type='octave') • SoundPowerIntensityResult
SoundPowerIntensityResult	dataclass	Scanning sound power. • partial_power, partial_power_level • sound_power [W], sound_power_level [dB] (NaN where negative_band) • negative_band: per-band bool (True where P ≤ 0) • surface_pressure_intensity_index (FpI) • negative_partial_power_index (F+/-) • repeatability, dynamic_capability_index (Ld) • achieved_grade • surface_area, sound_power_level_a, grade	ir.sound_power_level, ir.achieved_grade
sound_power_intensity_points	function	Sound power at discrete points (ISO 9614-1). • normal_intensity: (N, N_bands) signed Ini [W/m²] • areas: segment Si [m²] • pressure_levels: Lpi for F2/F3 • pressure_residual_index: δpI0 [dB] (criterion 1) • temporal_intensity: M short-time samples (F1) • frequencies [Hz] (criterion 2, Table B.2) • band_type: 'third' (Default)/'octave' • grade: 'precision'/'engineering' (Default)/'survey'	dp = emission.sound_power_intensity_points(i_n, areas, frequencies=f, band_type='octave') • DiscretePointIntensityResult
DiscretePointIntensityResult	dataclass	Discrete-point sound power. • partial_power Pi = Ini·Si (Eq. 11) • sound_power [W], sound_power_level [dB] (NaN where not_applicable_band, clause 9.2) • f1…f4: Annex A indicators • dynamic_capability_index (Ld), criterion_1, negative_power_within_limit, criterion_2, minimum_positions (C·F4²) • achieved_grade per band ('precision'/'engineering'/'none') • confidence_interval (Eq. B.3), expanded_uncertainty (2s at the grade achieved, clause 10.6; NaN where none was) • surface_area, positions, sound_power_level_a, a_weighting_omitted_bands • field_nonuniformity_a, achieved_grade_a, grade • .required_actions() → Table B.3 codes, .plot()	dp.achieved_grade, dp.required_actions()
ActionCode	enum	ISO 9614-1 Table B.3 corrective actions. • .value: the printed letter a…e • .criterion: the Table B.3 row • .action: what to change	[a.value for a in dp.required_actions()[0]]
position_count_factor	function	Criterion-2 factor C (ISO 9614-1 Table B.2). • grade: 'precision'/'engineering'/'survey' • frequency [Hz], or None for the A-weighted row (grade 3 only) • band_type: 'third' (Default)/'octave'	C = emission.position_count_factor('engineering', 1000.0) • per-band C for grades 1/2; grade 3 raises (A-weighted only)
determination_standard_deviation	function	Standard deviation s (ISO 9614-1 Table 2). • grade, frequency (or None for A-weighted), band_type • footnote 1: the true LW lies within ±2s at 95 %	s = emission.determination_standard_deviation('precision', 1000.0)
error_factor	function	Error factor Δ (ISO 9614-1 Table B.1). • grade • a_weighted: read the A-weighted row (grade 3 only) (Default: False)	d = emission.error_factor('engineering') • 0.20 / 0.29 / 0.60
normal_intensity_from_levels	function	Signed Ini from printed levels (ISO 9614-1 clause 9.1). • levels: XX [dB] • negative: the (-) of the print, broadcast per position	i_n = emission.normal_intensity_from_levels(lvl, negative=mask) • Ini = ±I0·10^(XX/10) [W/m²]
partial_power_concentration	function	Optional procedure of ISO 9614-1 8.3.2/B.1.3. • normal_intensity, areas: one band • grade: selects Δ (Table B.1)	c = emission.partial_power_concentration(i_n, areas) • PartialPowerConcentration
PartialPowerConcentration	dataclass	Concentrated positive partial power. • positions N, subset_positions Nα, subset_area Sα • power_fraction α, subset_nonuniformity F4(α), remainder_nonuniformity F4(1−α) • error_factor Δ, subset_error_factor Δα • additional_positions N* (Eq. B.4)	c.additional_positions
absorption_area	function	Equivalent absorption area (ISO 354 Eq. 5/7). • t60: T [s] • volume V [m³] • temperature_c [°C] (Default: 20) • speed_of_sound [m/s] (overrides temperature) • m: air attenuation [1/m] (Default: 0)	A = materials.absorption_area(t60, volume=200) • A [m²]
absorption_coefficient	function	Sound absorption coefficient (ISO 354 Eq. 9). • t1, t2: empty / with-specimen T [s] • volume V [m³] • sample_area S [m²] • temperature1_c/temperature2_c [°C] • speed_of_sound1/2, m1/m2	a = materials.absorption_coefficient(t1, t2, 200, 10.8) • α_s (unclamped, may exceed 1)
attenuation_from_alpha	function	ISO 9613-1 α → m (ISO 354 8.1.2.1). • alpha: attenuation [dB/m]	m = materials.attenuation_from_alpha(0.01) • m = α/(10 lg e) [1/m]
measure_sound_absorption	function	Reverberation-room absorption measurement (ISO 354 Eq. 5/7/8/9). • frequencies [Hz], t_empty T1 [s], t_specimen T2 [s] • volume V [m³], area S [m²] • temperature_c [°C] (Default: 20), relative_humidity_percent [%] • speed_of_sound [m/s], m [1/m] (Default: 0)	r = materials.measure_sound_absorption(f, t1, t2, volume=200, area=10.8) • SoundAbsorptionMeasurement
SoundAbsorptionMeasurement	dataclass	Reverberation-room sound absorption (ISO 354). • frequencies [Hz], t_empty/t_specimen [s] • volume, area, temperature_c, relative_humidity_percent, speed_of_sound • air_attenuation m [1/m] • absorption_area_empty A1, absorption_area_with_specimen A2 [m²] • alpha_s (unclamped) • .equivalent_absorption_area AT = A2−A1 • .plot() / .report()	r.alpha_s, r.equivalent_absorption_area
air_attenuation	function	Atmospheric attenuation coefficient α (ISO 9613-1 Eq. 5). • frequencies [Hz] • temperature_c [°C] (Default: 20) • relative_humidity_percent [%] (Default: 50) • atmospheric_pressure_kpa [kPa] (Default: 101.325) • exact_midband: snap to Table 1 midbands (Default: False)	a = environment.air_attenuation([1000, 4000], 20, 50) • α [dB/m] (×1000 = dB/km); out-of-range warns
air_attenuation_m	function	ISO 354 power attenuation m from conditions (ISO 9613-1 + ISO 354). • Same parameters as air_attenuation	m = environment.air_attenuation_m([1000, 4000], 20, 50) • m = α/(10 lg e) [1/m]
AtmosphericAbsorptionWarning	warning class	ISO 9613-1 out-of-range advisory. Emitted by air_attenuation when temperature/humidity/frequency leave the tabulated ranges or pressure exceeds 200 kPa, and by emission.air_absorption_np_per_m (so also by emission.room_constant_from_air_absorption and emission.free_field_absorption_correction) outside 50 Hz to 22.4 kHz, the ISO 9613-1 range as ISO 9295 Annex A extends it, or outside its temperature and humidity ranges; the result still returns	warnings.simplefilter('error', AtmosphericAbsorptionWarning)
atmospheric_attenuation	function	Plottable ISO 9613-1 attenuation-coefficient curve. • Same parameters as air_attenuation • distance d [m] (optional; enables total attenuation)	res = environment.atmospheric_attenuation([1000, 4000], 20, 50) • AtmosphericAttenuation; res.plot()
AtmosphericAttenuation	dataclass	Atmospheric attenuation result (ISO 9613-1). • frequencies [Hz] • attenuation_coefficient α [dB/m] • temperature_c, relative_humidity_percent, atmospheric_pressure_kpa • distance [m] or None • .total_attenuation A = α·d [dB] (ISO 9613-2 Aatm) or None • .plot(): α (dB/km) vs frequency	res.attenuation_coefficient, res.total_attenuation
geometric_divergence	function	Geometrical divergence Adiv (ISO 9613-2 Eq. 7). • distance d [m]	a = environment.geometric_divergence(100.0) • 20 lg(d/d₀) + 11 = 51 dB at 100 m
atmospheric_absorption	function	Atmospheric absorption term Aatm (ISO 9613-2 Eq. 8), α at the exact base-10 midbands (the Table 2 convention). • distance d [m] • frequencies [Hz] (snapped to exact midbands) • temperature_c/relative_humidity_percent/atmospheric_pressure_kpa	aatm = environment.atmospheric_absorption(200, bands) • α·d per band [dB]
ground_attenuation	function	Ground effect Agr, general method (ISO 9613-2 7.3.1, Eq. 9). • distance d, source_height hs, receiver_height hr [m] • frequencies [Hz] • ground_source/ground_middle/ground_receiver G ∈ [0,1] • projected_distance dp [m]	agr = environment.ground_attenuation(200, 2, 2, bands, 1, 1, 1) • As+Ar+Am per band [dB] (negative = gain)
ground_attenuation_alternative	function	Ground effect Agr, A-weighted method (ISO 9613-2 7.3.2, Eq. 10). • distance d [m] • mean_height hm [m]	agr = environment.ground_attenuation_alternative(200, 2) • 4.8 − (2hm/d)·(17+300/d) ≥ 0 [dB]
directivity_omega	function	Solid-angle directivity index DΩ (ISO 9613-2 Eq. 11). • source_height hs, receiver_height hr, projected_distance dp [m]	dw = environment.directivity_omega(1.5, 1.5, 200) • 0…~3 dB (add to Dc for the 7.3.2 method)
region_ground_factors	function	Ground factors of the three regions of a path over mixed ground (ISO/TR 17534-3 6.2.5). • segment_lengths [m], segment_ground_factors G, in order from the source • source_height hs, receiver_height hr [m]	g = environment.region_ground_factors([40.9, 102.2, 51.1], [0.9, 0.5, 0.2], 1, 4) • GroundFactors (Gs, Gm, Gr), each a length-weighted mean over its region
mean_path_height	function	Mean path height hm above a ground profile (ISO 9613-2 Figure 3). • profile_distances [m], strictly increasing, profile_heights [m] • source_height hs, receiver_height hr [m] • distance d [m] (Default: the slant distance the profile implies)	hm = environment.mean_path_height([0, 112.4, 178.8, 194.2], [0, 0, 10, 10], 1, 4) • hm = F/d [m], for the 7.3.2 method
Barrier	dataclass	Barrier diffraction geometry (ISO 9613-2 7.4). • source_to_edge dss, edge_to_receiver dsr [m] • parallel_distance a [m] (Default: 0) • edge_separation e [m] (Default: None → single diffraction) • ground_reflections_by_image (Default: False → C₂=20) • lateral (Default: False → top-edge) • line_of_sight_clear (Default: False; True gives z the negative sign of Eq. 16 when the sight line passes above the edge)	b = environment.Barrier(source_to_edge=101, edge_to_receiver=101) • .is_double when e is given
barrier_attenuation	function	Barrier diffraction Dz (ISO 9613-2 Eq. 14). • barrier: Barrier • distance d [m] • frequencies [Hz]	dz = environment.barrier_attenuation(b, 200, bands) • 10 lg[3+(C₂/λ)C₃ z Kmet], capped 20/25 dB; 10 lg 3 at grazing (z = 0), decaying to ≥ 0 for negative z
measured_insertion_loss_direct / measured_insertion_loss_indirect / MeasuredBarrierInsertionLoss	function / function / dataclass	What a barrier is worth once it is built, ISO 10847 8.2.1 and 8.2.2. • direct: D_IL = (L_ref,A − L_ref,B) − (L_r,A − L_r,B), the reference microphone normalising whatever the source did differently between campaigns • indirect: the "before" pair comes from an equivalent site, which makes it an estimate, and each campaign carries its receiver correction C_r • receiver_type_before / receiver_type_after: 'hemi_free_field' (Default, 0 dB) or 'reflecting_surface' (6 dB) • result: insertion_loss_db, method, the four spectra and the two corrections, .plot()	environment.measured_insertion_loss_direct(ref_b, ref_a, rec_b, rec_a, frequencies=f)
barrier_background_correction_db / ISO10847_BACKGROUND_CORRECTIONS_DB / ISO10847_MINIMUM_BACKGROUND_MARGIN_DB / ISO10847_PREFERRED_BACKGROUND_MARGIN_DB	function / mapping / constant	Table 3 of ISO 10847, in decibels to add. • 2 dB comes off at a margin of 4 or 5 dB, 1 dB from 6 to 9 dB, nothing from 10 dB up, which is the margin 6.4 asks for in the first place • the column reads "correction to be made to", so the values are negative and are added, where ISO 11820 prints the same physical thing positive and subtracts it • under 4 dB the results "are not valid", which is a refusal	environment.barrier_background_correction_db([5.0, 7.0]) # -2.0, -1.0
wind_class / WIND_CLASSES / MAXIMUM_WIND_SPEED_M_S / WIND_VECTOR_TOLERANCE_M_S / TEMPERATURE_TOLERANCE_C / CLOUD_COVER_CLASSES	function / mapping / constant	The weather the two campaigns have to share, ISO 10847 Table 1 and 6.2. • the vector component of the wind on the source-to-receiver line: positive downwind, negative upwind • downwind 1 m/s to 5 m/s and calm ± 1 m/s over any distance; the upwind class exists over short distances alone • past 5 m/s no measurement is made, which is a refusal rather than a class • the two campaigns must agree within 2 m/s on the component and 10 °C on the temperature, and the cloud cover is recorded in the four classes of Table 2	environment.wind_class(2.5) # 'downwind'
is_short_distance / SHORT_DISTANCE_RATIO / LONG_DISTANCE_M / CLOSE_SOURCE_DISTANCE_M / POINT_SOURCE_DIVERGENCE_DB / LINE_SOURCE_DIVERGENCE_DB	function / constant	Short distance or long? ISO 10847 6.3.1, and what hangs on it. • (H_s + H_R)/(d₁ + d₂) > 0,1 for the "before" campaign, and both of (H_s + H)/d₁ and (H + H_R)/d₂ > 0,1 for the "after" one • the inequalities are strict, so exactly 0,1 is not a short distance • only a short distance may be measured into the wind; beyond 250 m the standard stops claiming the method at all • 6 dB per doubling for a point source and 3 dB for a line one, the divergence the geometry is read against	environment.is_short_distance(source_height_m=1.0, receiver_height_m=1.5, barrier_height_m=4.0, source_to_barrier_m=10.0, barrier_to_receiver_m=20.0)
reference_microphone_height_m / REFERENCE_MICROPHONE_CLEARANCE_M / REFERENCE_ELEVATION_INCREMENT_DEG / MINIMUM_RECEIVER_HEIGHT_M / MINIMUM_REPETITIONS	function / constant	Where the two microphones stand, ISO 10847 7.2.2 and 7.3. • the reference microphone at least 1,5 m above the top edge of the barrier, measured from its highest point where the top is not a straight edge • for a source region nearer than 15 m the NOTE raises it further, until the elevation angle exceeds the angle to the top by 10°; the NOTE never lowers it, so this returns the higher of H + 1,5 m and d tan(arctan(H/d) + 10°) • where the top already stands 80° or more above the source region no height reaches the 10°: the clearance is returned and a BarrierInSituWarning emitted • a receiver stands at 1,2 m or higher, and the measurement is repeated at least three times	environment.reference_microphone_height_m(4.0, source_to_barrier_m=8.0)
hemi_free_field_distance_m / HEMI_FREE_FIELD_DISTANCE_M / HEMI_FREE_FIELD_DISTANCE_FACTOR / RECEIVER_CORRECTIONS_DB / EQUIVALENT_SURROUNDINGS_RADIUS_M / EQUIVALENT_SECTOR_DEG	function / constant / mapping	What makes a receiver position a free field, and a site an equivalent one, ISO 10847 8.1.2 and 6.1. • min(30 m, 2 d) to any vertical reflecting surface, so a receiver close behind the barrier needs less clearance rather than more, the two rules crossing at 15 m • a microphone against a facade instead carries the 6 dB of RECEIVER_CORRECTIONS_DB • an equivalent site matches over 30 m around the receiver and over a 60° sector towards the source	environment.hemi_free_field_distance_m(10.0) # 20.0
ISO10847_OCTAVE_BAND_RANGE_HZ / ISO10847_OCTAVE_BAND_EXTENDED_RANGE_HZ / ISO10847_THIRD_OCTAVE_BAND_RANGE_HZ / ISO10847_THIRD_OCTAVE_BAND_EXTENDED_RANGE_HZ	constant	The bands ISO 10847 measures in, clause 5. • 63 Hz to 4 kHz in octaves and 50 Hz to 5 kHz in one-third octaves • the extended ranges reach 8 kHz and 10 kHz where the source or the barrier asks for them	environment.ISO10847_OCTAVE_BAND_RANGE_HZ # (63.0, 4000.0)
BarrierInSituWarning	warning class	The measurement is outside a condition ISO 10847 states. • a distance past 250 m, a reference microphone with less clearance than 7.2.2 asks for, a receiver lower than 1,2 m, campaigns whose weather does not match	warnings.catch_warnings() Emitted by environment.propagation.barrier_in_situ
meteorological_correction	function	Meteorological correction Cmet (ISO 9613-2 Eq. 21/22). • projected_distance dp, source_height hs, receiver_height hr [m] • c0: factor C₀ [dB]	c = environment.meteorological_correction(200, 1.5, 1.5, 2.0) • C₀[1 − 10(hs+hr)/dp] ≥ 0 [dB]
outdoor_propagation_attenuation	function	Total octave-band attenuation A (ISO 9613-2 Eq. 4). • distance d, source_height hs, receiver_height hr [m] • frequencies [Hz] • ground_source/ground_middle/ground_receiver G • barrier: Barrier or None • temperature_c/relative_humidity_percent/atmospheric_pressure_kpa (Default: 20 °C/70 %/101.325 kPa, a Table 2 reference atmosphere) • projected_distance dp [m]	att = environment.outdoor_propagation_attenuation(200, 2, 2, bands, 1, 1, 1) • OutdoorAttenuation term breakdown
predicted_receiver_level	function	Predicted octave-band receiver level (ISO 9613-2 Eq. 3/6). • sound_power_level Lw [dB] • geometry: PropagationGeometry • frequencies [Hz] • ground: GroundFactors, barrier: Barrier, atmosphere: AtmosphericConditions • directivity: DirectivityCorrection • c0: subtract Cmet (Default: None)	lp = environment.predicted_receiver_level(lw, environment.PropagationGeometry(200, 2, 2), frequencies=bands) • LfT(DW) = Lw + Dc − A per band [dB]
OutdoorAttenuation	dataclass	Per-band ISO 9613-2 attenuation breakdown. • frequencies [Hz] • a_div, a_atm, a_gr, a_bar [dB] • a_total = Adiv+Aatm+Agr+Abar [dB] • d_omega [dB] • .report() one-page ISO 9613-2 prediction fiche (pass a SourceEmission for the A-weighted receiver level)	att.a_div, att.a_bar, att.a_total
SourceEmission	dataclass	Source emission for the receiver-level fiche (ISO 9613-2 Eq. 3), report-time only. • sound_power_level Lw [dB] • directivity_index Di [dB] (Default: 0) • d_omega DΩ [dB] (Default: 0) • cmet Cmet [dB] (Default: None)	att.report("f.pdf", source_emission=environment.SourceEmission(lw))
PropagationGeometry	dataclass	Source-to-receiver geometry of the ISO 9613-2 path. • distance d [m] • source_height hs, receiver_height hr [m] • projected_distance dp [m] (Default: None → √(d²−(hs−hr)²))	PropagationGeometry(200.0, 1.5, 1.5)
GroundFactors	dataclass	Ground factors G of the three regions (ISO 9613-2 7.3.1). • source Gs, middle Gm, receiver Gr ∈ [0,1] (Default: 0, hard ground)	GroundFactors(1.0, 1.0, 1.0) # porous
AtmosphericConditions	dataclass	Air state behind Aatm (ISO 9613-2 Eq. 8). • temperature_c [°C] (Default: 20) • relative_humidity_percent [%] (Default: None → 70) • atmospheric_pressure_kpa [kPa] (Default: 101.325)	AtmosphericConditions(temperature_c=15.0)
DirectivityCorrection	dataclass	Directivity correction Dc = Di + DΩ (ISO 9613-2 Eq. 3). • index Di [dB] (Default: 0) • d_omega DΩ [dB] (Default: 0)	DirectivityCorrection(index=3.0)
DEFAULT_FREQUENCIES	tuple	ISO 9613-2 nominal octave bands. (no parameters)	DEFAULT_FREQUENCIES # (63, …, 8000)
railway_source_power	function	CNOSSOS-EU railway source line power at the two source heights (Directive 2002/49/EC Annex II, 2.3.1). • traffic: one RailwayVehicle or a sequence • track: the RailwayTrack of the section • psi/phi [deg]: receiver angles (Default: 0 / 90, broadside) • reference_time Tref (Default: 12) • minimum_speed [km/h] (Default: 50, or 30 for a tram; 0 switches the floor off) • interpolation (RoughnessInterpolation), directivity_edition (DirectivityEdition)	res = environment.railway_source_power(environment.RailwayVehicle(stock, 96.0, 160.0), track) • RailwayEmissionResult
RailwayEmissionResult	dataclass	CNOSSOS-EU railway source-line power per metre. • third_octave_frequencies (50…10000 Hz), frequencies (63…8000 Hz) • heights (0.5, 4.0) m • third_octave_line_power (2, 24), line_power (2, 8) [dB re 1 pW/m] • total_line_power (8,) • components: rolling / traction / aerodynamic / bridge, per height • .plot()	res.total_line_power, res.components["rolling"]
RailwayVehicle	dataclass	One vehicle of the traffic on a track section. • stock: RollingStock • flow_rate Q [veh/h], speed v [km/h] • condition: RunningCondition • idling_time Tidle	RailwayVehicle(stock, flow_rate=96.0, speed=160.0)
RollingStock	dataclass	Appendix G data of one vehicle type. • axles Na • wheel_roughness, contact_filter: (wavelengths [mm], levels [dB]) • wheel_transfer, superstructure_transfer: 24 bands [dB/axle] • traction, aerodynamic: (source A, source B) • aerodynamic_alpha (Default: 50) • tram (Default: False)	RollingStock(axles=4, wheel_roughness=..., ...)
RailwayTrack	dataclass	Appendix G data of one track section. • rail_roughness, impact_roughness: (wavelengths [mm], levels [dB]) • track_transfer, bridge_transfer: 24 bands [dB/axle] • joint_density nl [1/m] (Default: 0.01) • squeal_excess [dB], length L [m] (Default: 100)	RailwayTrack(rail_roughness=..., track_transfer=...)
roughness_to_frequency	function	Resample a roughness spectrum from wavelength onto frequency, λ = v/f with v in m/s (Annex II 2.3.2 as corrected in 2018). • levels [dB], wavelengths [mm], speed [km/h] • frequencies [Hz], interpolation	lr = environment.roughness_to_frequency(levels, lam, 160.0)
total_effective_roughness	function	Total effective roughness LR,TOT (Annex II 2.3.7). • rail, wheel, filter_: 24 bands [dB]	ltot = environment.total_effective_roughness(rail, wheel, a3) • 10 lg(10^(LrTR/10)+10^(LrVEH/10)) + A3
impact_roughness	function	Impact roughness at a joint density (Annex II 2.3.12). • single: Table G-4 on the frequency grid [dB] • joint_density nl [1/m]	li = environment.impact_roughness(single, 0.03) • + 10 lg(nl/0.01)
rolling_sound_power	function	One rolling-noise component (Annex II 2.3.8 to 2.3.10). • roughness LR,TOT, transfer LH [dB] • axles Na	lw = environment.rolling_sound_power(ltot, environment.track_transfer("M/M"), 4) • LR,TOT + LH + 10 lg(Na)
curve_squeal_excess	function	Curve-squeal excess added to rolling noise (as replaced by (EU) 2021/1226 pt (4)(b)). • radius R [m] • tram, turnout (Default: False) • track_length ltrack [m] (Default: 50)	curve_squeal_excess(280.0) # 8.0 dB
horizontal_directivity	function	Horizontal dipole directivity (Annex II 2.3.15). • phi [deg] • frequencies [Hz]	horizontal_directivity(90.0) # 0 dB broadside
vertical_directivity	function	Vertical directivity of source A or B (Annex II 2.3.16/2.3.17). • psi [deg], frequencies [Hz] • height 1 or 2 • aerodynamic (height 2 only) • edition: DirectivityEdition	vertical_directivity(30.0)
aerodynamic_sound_power	function	Aerodynamic sound power at a speed (Annex II 2.3.13/2.3.14 with Table G-6). • speed v [km/h] (Default: 300) • reference: (source A, source B) at v0 • alpha (Default: 50)	low, high = environment.aerodynamic_sound_power(320.0)
octave_bands_from_third_octaves	function	Energy-sum 24 1/3-octave levels into the 8 octave bands (Annex II 2.3.2). • levels [dB]	octave_bands_from_third_octaves(res.third_octave_line_power[0])
wheel_roughness	function	Wheel roughness Lr,VEH of Table G-1a. • brake: BrakeType	lam, lr = environment.wheel_roughness(BrakeType.NON_TREAD)
rail_roughness	function	Rail roughness Lr,TR of Table G-1b (as replaced by (EU) 2021/1226). • roughness: RailRoughnessClass (only E and M are tabulated)	lam, lr = environment.rail_roughness(RailRoughnessClass.NORMAL)
contact_filter	function	Contact filter A3 of Table G-2 (as replaced by (EU) 2021/1226). • filter_: ContactFilter or (wheel load [kN], wheel diameter [mm])	lam, a3 = environment.contact_filter(ContactFilter.LOAD_50_DIAMETER_920)
track_transfer	function	Track transfer function LH,TR of Table G-3a (as replaced by (EU) 2021/1226). • track: TrackTransferClass or its column code	track_transfer("M/M") # 24 bands [dB/axle]
wheel_transfer	function	Wheel transfer function LH,VEH of Table G-3b. • diameter_mm: WheelDiameter or the diameter_mm [mm]	wheel_transfer(920.0)
superstructure_transfer	function	Superstructure transfer LH,VEH,SUP of Table G-3c (freight only; 0,0 dB everywhere). (no parameters)	superstructure_transfer()
impact_roughness_single	function	Single-impact roughness of Table G-4 (as replaced by (EU) 2021/1226), for nl = 0,01 per m. (no parameters)	lam, li = environment.impact_roughness_single()
traction_sound_power	function	Traction sound power of Table G-5; constant speed and idling are equal. • vehicle: TractionVehicle	low, high = environment.traction_sound_power(TractionVehicle.ELECTRIC_LOCO)
bridge_transfer	function	Bridge transfer function LH,bridge of Table G-7 (as replaced by (EU) 2021/1226). • bridge: BridgeType	bridge_transfer(BridgeType.PLUS_10_DBA)
VehicleDescriptor	dataclass	Four-digit vehicle descriptor of Table [2.3.a]. • vehicle_type, axles, brake, measure • .from_code(), .code	VehicleDescriptor.from_code("a4cn")
TrackDescriptor	dataclass	Six-digit track descriptor of Table [2.3.b]. • base, roughness, pad, measure, joints, curvature • .from_code(), .code	TrackDescriptor.from_code("BMSNNH")
VehicleType	enum	Digit 1 of the vehicle descriptor. HIGH_SPEED (h), SELF_PROPELLED (m), HAULED (p), CITY_TRAM (c), DIESEL_LOCO (d), ELECTRIC_LOCO (e), FREIGHT (a), OTHER (o)	VehicleType.FREIGHT
BrakeType	enum	Digit 3 of the vehicle descriptor. CAST_IRON (c), COMPOSITE (k), NON_TREAD (n)	BrakeType.CAST_IRON
WheelMeasure	enum	Digit 4 of the vehicle descriptor. NONE (n), DAMPERS (d), SCREENS (s), OTHER (o)	WheelMeasure.DAMPERS
TrackBase	enum	Digit 1 of the track descriptor. BALLAST (B), SLAB (S), BALLASTED_BRIDGE (L), NON_BALLASTED_BRIDGE (N), EMBEDDED (T), OTHER (O)	TrackBase.BALLAST
RailRoughnessClass	enum	Digit 2 of the track descriptor. WELL_MAINTAINED (E), NORMAL (M), NOT_WELL_MAINTAINED (N), BAD (B)	RailRoughnessClass.NORMAL
RailPad	enum	Digit 3 of the track descriptor, the rail-pad dynamic stiffness. SOFT (S, 150-250 MN/m), MEDIUM (M, 250-800 MN/m), HARD (H, 800-1 000 MN/m)	RailPad.MEDIUM
TrackMeasure	enum	Digit 4 of the track descriptor. NONE (N), RAIL_DAMPER (D), LOW_BARRIER (B), ABSORBER_PLATE (A), EMBEDDED_RAIL (E), OTHER (O)	TrackMeasure.RAIL_DAMPER
RailJoints	enum	Digit 5 of the track descriptor. NONE (N), SINGLE (S), TWO (D), MORE (M)	RailJoints.SINGLE
TrackCurvature	enum	Digit 6 of the track descriptor. STRAIGHT (N), LOW (L), MEDIUM (M), HIGH (H)	TrackCurvature.HIGH
TrackTransferClass	enum	Columns of Table G-3a (track base / rail pad). MONOBLOCK_SOFT, MONOBLOCK_MEDIUM, MONOBLOCK_HARD, BIBLOCK_SOFT, BIBLOCK_MEDIUM, BIBLOCK_HARD, WOODEN, DIRECT_FASTENING	TrackTransferClass.WOODEN
WheelDiameter	enum	Columns of Table G-3b, the wheel diameter [mm]. MM_920, MM_840, MM_680, MM_1200	WheelDiameter.MM_920
ContactFilter	enum	Columns of Table G-2, (wheel load [kN], wheel diameter [mm]). LOAD_50_DIAMETER_360, LOAD_50_DIAMETER_680, LOAD_50_DIAMETER_920, LOAD_25_DIAMETER_920, LOAD_100_DIAMETER_920	ContactFilter.LOAD_25_DIAMETER_920
TractionVehicle	enum	Columns of Table G-5. DIESEL_LOCO_800, DIESEL_LOCO_2200, DIESEL_MULTIPLE_UNIT, ELECTRIC_LOCO, ELECTRIC_MULTIPLE_UNIT	TractionVehicle.DIESEL_LOCO_2200
BridgeType	enum	Columns of Table G-7, labelled by the A-weighted bridge excess. PLUS_10_DBA, PLUS_15_DBA	BridgeType.PLUS_15_DBA
RunningCondition	enum	Running condition c of Annex II 2.3.2. CONSTANT (1), IDLING (2)	RunningCondition.IDLING
DirectivityEdition	enum	Which text of the vertical directivity (2.3.16) to evaluate. CURRENT ((EU) 2021/1226: zero for ψ ≤ 0), ORIGINAL_2015 (absolute-value bars over the whole range)	DirectivityEdition.ORIGINAL_2015
RoughnessInterpolation	enum	How a roughness spectrum is resampled from wavelength onto frequency (Annex II gives prose, not a formula). PROPORTIONAL (levels, the Commission reference module's rule), ENERGY (energies)	RoughnessInterpolation.ENERGY
RAILWAY_THIRD_OCTAVE_BANDS	tuple	The 24 1/3-octave bands of the railway source (50 Hz…10 kHz). (no parameters)	RAILWAY_THIRD_OCTAVE_BANDS
RAILWAY_OCTAVE_BANDS	tuple	The 8 octave bands handed to propagation (63 Hz…8 kHz). (no parameters)	RAILWAY_OCTAVE_BANDS
RAILWAY_SOURCE_HEIGHTS	tuple	Heights of the two equivalent source lines (Annex II 2.3.1). (no parameters)	RAILWAY_SOURCE_HEIGHTS # (0.5, 4.0)
RAILWAY_MINIMUM_SPEED	float	Speed floor used to determine the total effective roughness [km/h]. (no parameters)	RAILWAY_MINIMUM_SPEED # 50.0
TRAM_MINIMUM_SPEED	float	The same floor for trams and light metro [km/h]. (no parameters)	TRAM_MINIMUM_SPEED # 30.0
AERODYNAMIC_THRESHOLD_SPEED	float	Speed above which aerodynamic noise is relevant [km/h]. (no parameters)	AERODYNAMIC_THRESHOLD_SPEED # 200.0
AERODYNAMIC_REFERENCE_SPEED	float	Reference speed v0 of Annex II 2.3.13/2.3.14 [km/h]. (no parameters)	AERODYNAMIC_REFERENCE_SPEED # 300.0
REFERENCE_JOINT_DENSITY	float	Joint density Table G-4 is given for [1/m]. (no parameters)	REFERENCE_JOINT_DENSITY # 0.01
road_source_power	function	CNOSSOS-EU road source line power (Directive 2002/49/EC Annex II, 2.2.1). • traffic: one RoadTraffic or a sequence, at most one per category • surface: RoadSurface, its description or a RoadSurfaceCoefficients (Default: reference surface) • temperature_c tau [°C] (Default: 20) • road_slope_percent s [%] (Default: 0, positive uphill) • studded_months Ts (Default: 0) • junction_distance x [m], junction_type (JunctionType) • coefficients: Appendix F database (Default: ROAD_COEFFICIENTS)	res = environment.road_source_power([environment.RoadTraffic(RoadVehicleCategory.LIGHT, 1200, 50)]) • RoadEmissionResult
RoadTraffic	dataclass	Traffic of one vehicle category on a source line. • category: RoadVehicleCategory • flow_rate Qm [veh/h] • speed vm [km/h] (powers frozen below 20 km/h) • studded_fraction Qstud,ratio (Default: 0, category 1 only)	RoadTraffic(RoadVehicleCategory.HEAVY, 45.0, 50.0)
RoadEmissionResult	dataclass	CNOSSOS-EU road source-line power per metre. • frequencies [Hz] (63…8000) • categories • rolling, propulsion, vehicle_power, line_power: (N_cat, 8) [dB] • total_line_power [dB re 1 pW/m] • source_height (0.05 m) • .a_weighted_line_power [dB(A)] • .plot()	res.total_line_power, res.a_weighted_line_power
road_vehicle_sound_power	function	Single-vehicle sound power LW,i,m (Annex II 2.2.2/2.2.3). • category, speed [km/h] • same surface/temperature/gradient/studded/junction parameters as road_source_power	lw = environment.road_vehicle_sound_power("1", 90.0) • 8 octave bands [dB]; category 4 takes propulsion alone
road_rolling_noise	function	Rolling-noise sound power LWR,i,m (Annex II 2.2.4/2.2.5). • category, speed [km/h] • surface, temperature_c, studded_fraction, studded_months, junction_distance, junction_type, coefficients	lwr = environment.road_rolling_noise("1", 90.0, temperature_c=5.0) • AR + BR·lg(v/70) + ΔLWR per band
road_propulsion_noise	function	Propulsion-noise sound power LWP,i,m (Annex II 2.2.11/2.2.12). • category, speed [km/h] • surface, road_slope_percent, junction_distance, junction_type, coefficients	lwp = environment.road_propulsion_noise("3", 80.0, road_slope_percent=-8.0) • AP + BP·(v−70)/70 + ΔLWP per band
road_surface_coefficients	function	Table F-4 row of a road surface (as replaced by (EU) 2021/1226). • surface: RoadSurface or its description	row = environment.road_surface_coefficients(RoadSurface.THIN_LAYER_A) • RoadSurfaceCoefficients
RoadSurfaceCoefficients	dataclass	One Table F-4 row. • name • alpha: per category, 8 bands [dB] • beta: per category • speed_range (vmin, vmax) [km/h] or None	row.alpha["1"], row.beta["1"], row.speed_range
RoadEmissionCoefficients	dataclass	Appendix F database (Tables F-1 to F-3 + Km). • rolling_a/rolling_b/propulsion_a/propulsion_b: per category, 8 bands • studded_a/studded_b (Table F-2) • junction_c (Table F-3) • temperature_k Km [dB/°C]	ROAD_COEFFICIENTS.rolling_a["1"]
ROAD_COEFFICIENTS	dataclass	The consolidated Appendix F database. Tables F-1/F-4 as replaced by (EU) 2021/1226, F-2/F-3 as published in (EU) 2015/996	ROAD_COEFFICIENTS.propulsion_a["3"]
RoadVehicleCategory	enum	Vehicle categories of Table [2.2.a]. LIGHT (1), MEDIUM_HEAVY (2), HEAVY (3), MOPEDS (4a), MOTORCYCLES (4b)	RoadVehicleCategory.HEAVY.value # '3'
RoadSurface	enum	The fifteen road surfaces of Table F-4. REFERENCE, ONE_LAYER_ZOAB, TWO_LAYER_ZOAB, TWO_LAYER_ZOAB_FINE, SMA_NL5, SMA_NL8, BRUSHED_DOWN_CONCRETE, OPTIMISED_BRUSHED_DOWN_CONCRETE, FINE_BROOMED_CONCRETE, WORKED_SURFACE, HARD_ELEMENTS_HERRINGBONE, HARD_ELEMENTS_NOT_HERRINGBONE, QUIET_HARD_ELEMENTS, THIN_LAYER_A, THIN_LAYER_B	RoadSurface.QUIET_HARD_ELEMENTS
JunctionType	enum	Junction types k of Table F-3. NONE (0), CROSSING (1), ROUNDABOUT (2)	JunctionType.ROUNDABOUT
line_source_segment_power	function	Point-source power of a segment of source line (arithmetic; the split is outside the scope of Annex II 2.5.3). • line_power [dB re 1 pW/m] • length dL [m]	lw = environment.line_source_segment_power(res.total_line_power, 20.0) • L'W,eq,line + 10 lg(dL)
CNOSSOS_A_WEIGHTING	tuple	Octave-band A-weighting AWCf,i printed by Annex II 2.5.5 as amended by (EU) 2021/1226. (no parameters)	CNOSSOS_A_WEIGHTING # (-26.2, …, -1.1)
ROAD_OCTAVE_BANDS	tuple	CNOSSOS-EU road source octave bands (63 Hz…8 kHz, per the 2018 corrigendum to 2.2.1). (no parameters)	ROAD_OCTAVE_BANDS
ROAD_REFERENCE_SPEED / ROAD_REFERENCE_TEMPERATURE / ROAD_SOURCE_HEIGHT	float	Reference conditions of Annex II 2.2. vref = 70 km/h, tauref = 20 °C, source height 0,05 m	ROAD_REFERENCE_SPEED # 70.0
statistical_pass_by	function	Statistical Pass-By method of a road surface (ISO 11819-1:1997, 9.1 to 9.5). • vehicle_categories ("1" cars, "2a" dual-axle, "2b" multi-axle heavy) / speeds_kmh / max_levels_db (LAFmax): one row per pass-by • road_speed_category: "low"|"medium"|"high" (Table 1 reference speeds and weights) • corrected_vehicle_sound_levels_db: temperature-corrected L_veh (9.4 gives no method) • reference_db: reference surface SPBI or its three L_veh (clause 10) • weighting_factors: other proportions, summing to 1 • 7.3 counts and 9.3 speed windows emit StatisticalPassByWarning	res = environment.statistical_pass_by(cats, v, L, road_speed_category="medium") • StatisticalPassByResult
StatisticalPassByResult	dataclass	Vehicle sound levels and index of one surface. • regressions (per category) / vehicle_sound_levels_db / index_db (unrounded) • reported_vehicle_sound_levels_db / reported_index_db (one decimal, half up) • corrected_index_db / reference_index_db / .difference_db / .corrected_difference_db • .index_confidence_interval_db / .meets_minimum_counts / .reference_speeds_in_window • .plot(): the three clouds, their lines and L_veh	res.reported_index_db
pass_by_regression	function	Least-squares line of LAFmax on lg v for one category, read at the reference speed (9.1, 9.2). • speeds_kmh / max_levels_db • vehicle_category / road_speed_category	reg = environment.pass_by_regression(v, L, vehicle_category="1", road_speed_category="medium") • PassByRegression
PassByRegression	dataclass	One category's line and the clause 13 item 29 statistics. • intercept_db / slope_db_per_decade / correlation • level_standard_deviation_db / residual_standard_deviation_db (n − 2) / lg_speed_standard_deviation • .vehicle_sound_level_db / .reported_vehicle_sound_level_db / .mean_speed_kmh (10^mean lg v) • .speed_window_kmh / .reference_speed_in_window (9.3) / .meets_minimum_count (7.3) • .confidence_interval_db (95 %, Student t) / .plot()	reg.vehicle_sound_level_db
statistical_pass_by_index	function	SPBI of three vehicle sound levels (9.5). • vehicle_sound_levels_db: keyed "1", "2a", "2b" • road_speed_category / weighting_factors	environment.statistical_pass_by_index({"1": 78.5, "2a": 81.1, "2b": 83.8}, road_speed_category="medium") # 79.946…
normalized_reference_levels	function	L_veh of a normalized reference surface: the average of several surfaces (10.2, Annex D). • surface_levels_db: surface label → the three L_veh	normalized_reference_levels(SPB_ANNEX_D_SURFACES_DB)
StatisticalPassByWarning	warning class	ISO 11819-1 advisory. Emitted when a category falls short of the 7.3 minimum count or its reference speed leaves the 9.3 window	warnings.simplefilter('error', StatisticalPassByWarning)
SPB_REFERENCE_SPEEDS_KMH / SPB_WEIGHTING_FACTORS	mapping	Table 1: reference speeds [km/h] and weighting factors Wx, by road speed then vehicle category.	SPB_REFERENCE_SPEEDS_KMH["medium"]["1"] # 80.0
SPB_VEHICLE_STANDARD_DEVIATIONS_DB / SPB_CONFIDENCE_INTERVALS_DB	mapping	Table 2: expected spread of individual vehicles about L_veh and the 95 % interval it leaves [dB].	SPB_CONFIDENCE_INTERVALS_DB["1"] # 0.3
SPB_MINIMUM_VEHICLE_COUNTS / SPB_SPEED_WINDOW_STANDARD_DEVIATIONS	mapping	7.3 minimum vehicles for classification ("2" is 2a and 2b together) and the 9.3 window in standard deviations of speed.	SPB_MINIMUM_VEHICLE_COUNTS["2"] # 80
SPB_ANNEX_D_SURFACES_DB / SPB_NORMALIZED_REFERENCE_DB	mapping	Annex D: the seven surfaces of the example reference case and their average row [dB], medium speed range.	SPB_NORMALIZED_REFERENCE_DB["2b"] # 84.0
SPB_VEHICLE_CATEGORIES / SPB_ROAD_SPEED_CATEGORIES	constant	The category labels the method uses: ("1", "2a", "2b") and ("low", "medium", "high").	SPB_VEHICLE_CATEGORIES
SPB_REFERENCE_AIR_TEMPERATURE_C	float	9.4: the air temperature L_veh should be corrected to [°C].	SPB_REFERENCE_AIR_TEMPERATURE_C # 20.0
ground_effect	function	Spherical-wave ground effect ΔL (Weyl-Van der Pol; Attenborough 2e Eq. 2.40, Salomons Eq. 3.4). • frequencies [Hz], source_height hs, receiver_height hr, distance [m] • impedance (normalized) or flow_resistivity σ [Pa·s/m²] • model 'delany_bazley'/'miki'	r = environment.ground_effect(bands, 1, 1.5, 50, flow_resistivity=2e5) • SphericalGroundResult (ΔL, Q, Rp, F)
GroundSurface	dataclass	One ground surface as one published table prints it. • flow_resistivity_pa_s_m2 is an effective resistivity: the number that makes a rigid-framed ground model reproduce a measured attenuation, so it carries the fit it came from • porosity (a fraction), water_content_percent, porosity_decay_rate_per_m: what Cox tabulates beside it; the six porosities Cox prints in per cent in a column of fractions are None, and .why_missing('porosity') quotes them • iso_9613_ground_factor, nmpb_ground_factor, harmonoise_class: the class rows, where the two models disagree on two of the eight classes • The hedges every catalogue row has: ranges, reported, unquantified, uncertainty, approximate, variant	g = environment.PUBLISHED_GROUND['bies-2017-table-5-1/sugar_snow'] g.printed('flow_resistivity_pa_s_m2') • g.source prints the page
PUBLISHED_GROUND	mapping	A hundred and five ground surfaces from three published tables, keyed '<table>/<row>'. • Bies 5e Table 5.1, thirty-four measured surfaces, and Table 5.2, the eight classes A to H with the ISO 9613-2 and NMPB-2008 ground factors • Cox & D'Antonio 3e Table 6.7, sixty-three rows: the same surface fitted with three different models is three rows, because the fit is part of the quantity • Seven surfaces both books take from Embleton (1983) come out to the same digits through two different printed units • One cell of Cox prints 1.7.3 × 10⁵, with two decimal points; it is kept as the page printed it and answers None	environment.PUBLISHED_GROUND['bies-2017-table-5-2/normal_uncompacted_ground'] • GroundSurface, ground_surfaces_named
ground_surfaces_named	function	Every published row for a surface name, across the books. • name as a table prints it, matched without regard to case • Returns every reading rather than choosing one: the spread between books is the answer	environment.ground_surfaces_named('Sugar snow') • (GroundSurface, ...)
spherical_reflection_coefficient	function	Spherical-wave reflection coefficient Q = Rp + (1−Rp)F(w) (Attenborough Eq. 2.40c; Salomons Eq. D.58). • frequencies, normalized_impedance, source_height, receiver_height, distance	q = environment.spherical_reflection_coefficient(bands, 12-6j, 1, 1.5, 50)
SphericalGroundResult	dataclass	Spherical-wave ground-effect result. • excess_attenuation ΔL [dB re free field] • reflection_coefficient Q, plane_reflection_coefficient Rp, boundary_loss F • r_direct, r_reflected [m] • .plot()	r.excess_attenuation, r.reflection_coefficient
fresnel_number	function	Barrier Fresnel number N = (2/λ)(A+B−d) (Bies 5e Eq. 5.134). • source_to_edge A, edge_to_receiver B, direct_distance d [m] • frequencies [Hz]	n = environment.fresnel_number(101, 101, 200, bands)
kurze_anderson_attenuation	function	Kurze-Anderson barrier attenuation (Bies Eq. 5.138). • fresnel_number N	kurze_anderson_attenuation(0.0) # 5 dB
barrier_insertion_loss	function	Barrier insertion loss: Kurze-Anderson / exact half-plane / coherent ground four-path (Attenborough Ch. 9, Bies 5.3.5-5.3.7). • frequencies, source_height, barrier_distance, barrier_height, receiver_distance, receiver_height • method 'exact'/'kurze_anderson' • thickness e [m] (thick barrier) • ground_impedance or ground_flow_resistivity	il = environment.barrier_insertion_loss(bands, 1, 50, 4, 100, 1.5, ground_flow_resistivity=2e5) • BarrierInsertionLoss
TRAFFIC_NOISE_BANDS_HZ / NORMALISED_TRAFFIC_NOISE_SPECTRUM_DB / NORMALISED_RAILWAY_NOISE_SPECTRUM_DB / SPECTRA	constant	The eighteen one-third octave bands from 100 Hz to 5 kHz, and the two spectra a device is rated against: EN 1793-3 Table 1 for a road and EN 16272-3-1 Table 1 for a railway. SPECTRA maps 'road' and 'railway' to them.	environment.NORMALISED_TRAFFIC_NOISE_SPECTRUM_DB[10] # -8.0 dB at 1 kHz
sound_absorption_rating / airborne_insulation_rating	function	EN 1793-1 Clause 5, EN 1793-2 Clause 5.2 and EN 16272-3-1 Clauses 5 and 6: what a noise reducing device is declared by. • sound_absorption_rating(absorption_coefficients, spectrum='road'): DLα, the energy the device does not send back, capped by the 0,99 ratio limit both standards put on it • airborne_insulation_rating(sound_reduction_index_db, spectrum='road'): DL_R, the energy it does not pass • spectrum='railway' swaps in EN 16272-3-1 Clauses 5 and 6, which are the same formulas on the railway table and print no category ladder • both return a RoadDeviceRating carrying the unrounded value, the reported integer and, for a road device, its Annex A category	environment.airborne_insulation_rating([32.0] * 18).category # 'B3'
RoadDeviceRating	dataclass	One declared rating: rating, reported, category (None for a railway device), quantity, spectrum, bands_hz, values, weights. • .plot() draws the per-band input against the spectrum that weights it	rating.plot()
ABSORPTION_RATIO_LIMIT / ABSORPTION_CATEGORIES / INSULATION_CATEGORIES	constant	The 0,99 ceiling of EN 1793-1 Clause 5, and the two Annex A category ladders (A1 to A5, B1 to B4) read off the reported integer.	environment.ABSORPTION_RATIO_LIMIT # 0.99
RoadDeviceWarning	warning class	Emitted when the weighted absorption ratio reaches the 0,99 limit, so the rating is the limit rather than the measurement.	warnings.catch_warnings()
plot_barrier_geometry	function	Source-barrier-receiver section to scale. • source_height, barrier_distance, barrier_height, receiver_distance, receiver_height [m] • thickness [m] (Default: None → thin screen) • language	plot_barrier_geometry(source_height=1.5, barrier_distance=5.0, barrier_height=3.0, receiver_distance=20.0, receiver_height=1.5) • Direct + diffracted paths, path difference annotated; also BarrierInsertionLoss.plot_geometry()
BarrierInsertionLoss	dataclass	Per-band barrier insertion loss. • insertion_loss [dB], fresnel_number, method, ground • .plot() (IL vs frequency)	il.insertion_loss
linear_sound_speed_profile	function	Linear effective sound-speed profile c_eff(z) = c0 + g·z (Salomons Sec. 4.2). • gradient_per_s g [s⁻¹] • ground_speed c0 [m/s], max_height [m]	p = environment.linear_sound_speed_profile(0.1) • EffectiveSoundSpeedProfile
log_linear_sound_speed_profile	function	Logarithmic surface-layer profile c_eff(z) = c0 + b·ln(1+z/z0) (Salomons Eq. 4.5). • b [m/s] (downward > 0) • ground_speed c0, roughness_length z0, max_height [m], n_points	p = environment.log_linear_sound_speed_profile(1.0) • EffectiveSoundSpeedProfile
EffectiveSoundSpeedProfile	dataclass	Effective sound-speed profile c_eff(z). • heights z [m], sound_speeds [m/s], description • .speed_at(z), .plot()	p.speed_at(10.0)
ray_curvature_radius	function	Radius of curvature of a ray in a linear gradient_per_s Rc = c0/(|g| cos θ0) (Salomons Sec. 4.4). • gradient_per_s g [s⁻¹] • ground_speed c0 [m/s], launch_angle_deg θ0	ray_curvature_radius(0.1) # 3430 m
shadow_zone_distance	function	Shadow-boundary distance in upward refraction √(2Rc)(√hs+√hr) (Salomons Sec. 4.4). • gradient_per_s g < 0 [s⁻¹] • source_height hs, receiver_height hr [m] • ground_speed c0	shadow_zone_distance(-0.1, 2, 2)
atmospheric_ray_paths	function	Ray tracing through a refracting atmosphere (Snell's law, Salomons Eq. 4.3). • profile: EffectiveSoundSpeedProfile • source_height [m], launch_angles_deg • max_range [m], n_steps	r = environment.atmospheric_ray_paths(p, source_height=2, launch_angles_deg=[-2,0,2]) • AtmosphericRayResult
AtmosphericRayResult	dataclass	Ray-tracing solution. • ranges, heights, travel_times [s] • turning_points, ground_reflections • .plot() (ray paths)	r.heights, r.turning_points
atmospheric_parabolic_equation	function	Relative-level field from the Green's Function PE (Salomons App. H). • frequency_hz, profile, source_height [m] • impedance or flow_resistivity σ, model • max_range/max_height/range_step/height_step [m]	pe = environment.atmospheric_parabolic_equation(500, p, source_height=2, flow_resistivity=2e5) • AtmosphericPEResult
AtmosphericPEResult	dataclass	GFPE relative-level field (dB re free field). • ranges, heights, relative_level (z×r) • normalized_impedance • .level_at_height(z), .plot()	pe.level_at_height(2.0)
task_based_exposure	function	Task-based daily exposure LEX,8h + U (ISO 9612 Clause 9). • tasks: sequence of Task • instrument: 'class1'/'class2'/'personal_exposimeter' (Default) • u3 [dB] (Default: 1.0) • include_duration_uncertainty (Default: True) • warn (Default: True)	res = hearing.task_based_exposure(tasks) • ExposureResult with per-task breakdown
job_based_exposure	function	Job-based daily exposure LEX,8h + U (ISO 9612 Clause 10). • samples Lp,A,eqT [dB] • effective_duration_hours Te [h] • instrument, u3 • n_workers/sample_duration_hours: Table 1 check	res = hearing.job_based_exposure(samples, 7.5) • ExposureResult (Eq C.9 / Table C.4 budget)
full_day_exposure	function	Full-day daily exposure LEX,8h + U (ISO 9612 Clause 11). • samples whole-day Lp,A,eqT [dB] • effective_duration_hours Te [h] • instrument, u3, warn	res = hearing.full_day_exposure(samples, 9.25) • ExposureResult; 3 samples spanning ≥3 dB advise
Task	dataclass	One task of a task-based measurement (ISO 9612 Clause 9). • samples [dB], duration_hours [h] • duration_samples/duration_range (for u1b) • label, instrument	Task(samples=(80.1, 82.2), duration_hours=5.0)
ExposureResult	dataclass	Daily exposure and uncertainty (ISO 9612). • lex_8h [dB] • combined_standard_uncertainty u [dB] • expanded_uncertainty U = 1.65 u [dB] • upper_limit = LEX,8h + U [dB] • strategy, sampling_advisory, instrument, tasks • .report(path, ...): ISO 9612 Clause 15 measurement report with the Directive 2003/10/EC assessment → PDF	res.report("lex.pdf", metadata=ReportMetadata(client="..."))
TaskContribution	dataclass	Per-task breakdown inside ExposureResult.tasks (ISO 9612 Clause 9). • label, lp_aeqt (Eq. 7), duration_hours • lex_8h_contribution (Eq. 8) [dB] • uncertainty terms u1a, u1b, c1a, c1b, u2, u3	res.tasks[0].lex_8h_contribution
table_c4_contribution	function	Sampling contribution c₁u₁ [dB] from Table C.4 (ISO 9612 job/full-day). • n_samples: N (clamped to [3, 30]) • u1: sampling standard uncertainty [dB] • bilinear interpolation, anchored at u₁ = 0	table_c4_contribution(6, 2.0) # 1.4
minimum_cumulative_duration_hours	function	Minimum cumulative measurement duration [h] (ISO 9612 Table 1). • n_workers: group size n_G (> 40 → 17 h; the standard advises splitting the group)	minimum_cumulative_duration_hours(18) # 10.75
COVERAGE_FACTOR	float	ISO 9612 coverage factor k = 1.65 (Clause 14). One-sided 95 % confidence: U = 1.65 u, upper limit LEX,8h + U	COVERAGE_FACTOR # 1.65
real_ear_attenuation	function	The attenuation of a protector on a panel of subjects, its spread and its uncertainty (ISO 4869-1 4.6 and Annex A). • attenuation_db: (subjects, bands) individual attenuations [dB], or open_threshold_db with occluded_threshold_db (4.6.2: occluded minus open) • frequencies [Hz] (Default: 125 Hz to 8 kHz for seven bands, from 63 Hz for eight) • u = s/√N, U95 = 2u, at full precision	r = hearing.real_ear_attenuation(grid) • RealEarAttenuationResult; r.attenuation_db feeds assumed_protection_value, hml_rating and snr_rating unchanged
RealEarAttenuationResult	dataclass	ISO 4869-1 measurement. • attenuation_db, mean_db, standard_deviation_db, standard_uncertainty_db, expanded_uncertainty_db [dB] • frequencies [Hz], subjects • .plot(): mean attenuation downwards on the IEC 60263 grid, Clause 6 l)	r.expanded_uncertainty_db
assess_attenuation_difference	function	Do two attenuation measurements differ significantly? (ISO 4869-1 Annex B). • first, second: a RealEarAttenuationResult or its means [dB] • first_expanded_uncertainty_db, second_expanded_uncertainty_db: U95 for bare means [dB] • significant when |m1 − m2| > √(U95,1² + U95,2²)	d = hearing.assess_attenuation_difference(r1, r2) • AttenuationDifferenceResult (difference_db, criterion_db, significant, significant_frequencies, .plot())
AttenuationDifferenceResult	dataclass	Annex B verdict per band. • difference_db, criterion_db [dB], significant per band, any_significant • no truth value: read significant • .plot()	d.significant_frequencies
minimum_significant_difference	function	√2·U95, the minimum difference for two equal uncertainties (ISO 4869-1 B.1.1, B.2). • expanded_uncertainty_db [dB], a number or an array • B.1.1 feeds it the rounded 2,3 dB of Table A.2 and prints 3,3 dB	hearing.minimum_significant_difference(2.3) # 3.25
reat_expanded_uncertainty	function	Typical U95 per band from Table A.2 (within a laboratory) or B.2 (between laboratories). • frequencies [Hz] • protector: 'earplug' or 'earmuff' • between_laboratories (Default: False)	hearing.reat_expanded_uncertainty([250, 8000], protector='earplug')
ProtectorUncertaintyBudget	dataclass	The three standard uncertainties of Table A.1: method_db, equipment_db, environment_db [dB]. • combined_db = root sum of squares, expanded_db = 2u, both derived	hearing.REAT_WITHIN_LABORATORY_UNCERTAINTY['earmuff']['250 Hz up to 4 kHz'].expanded_db
REAT_WITHIN_LABORATORY_UNCERTAINTY / REAT_BETWEEN_LABORATORY_UNCERTAINTY	mapping	Tables A.2 and B.2 of ISO 4869-1: the typical budget by protector ('earplug', 'earmuff') and frequency range.	hearing.REAT_BETWEEN_LABORATORY_UNCERTAINTY['earplug']
REAT_FREQUENCY_RANGES	constant	The three columns of Tables A.2 and B.2: 'below 250 Hz', '250 Hz up to 4 kHz', 'above 4 kHz'.	hearing.REAT_FREQUENCY_RANGES
REAT_FIELD_VARIATION_LIMITS	constant	Table 1 of ISO 4869-1: (lowest free-field rejection, allowable field variation) [dB]. 25 → 20, 20 → 15, 15 → 10, 10 → 5; below 10 dB the microphone is not suitable	hearing.REAT_FIELD_VARIATION_LIMITS[0] # (25.0, 20.0)
allowable_field_variation	function	Table 1 lookup. • free_field_rejection_db [dB]; below 10 dB raises	hearing.allowable_field_variation(18.0) # 10.0
check_reat_sound_field	function	Is the test site's sound field diffuse enough? (ISO 4869-1 4.2.2). • position_levels_db: levels at 'front', 'back', 'left', 'right', 'up', 'down' [dB] • reference_levels_db [dB] • rotation_levels_db with free_field_rejection_db for b), from 500 Hz	c = hearing.check_reat_sound_field(levels, reference) • ReatSoundFieldCheck
ReatSoundFieldCheck	dataclass	4.2.2 verdict. • uniform (±2,5 dB), balanced (right-left 3 dB), diffuse (Table 1) per band • directionality_judged: whether b) was measured • passes needs a) and b); no truth value • .plot()	c.passes
assumed_protection_value	function	Assumed protection value APVfx = mf − α·sf (ISO 4869-2 Clause 5, Formula (1)). • attenuation: (subjects, bands) ISO 4869-1 grid [dB] • performance: 50/75/80/84/90/95/98 % from Table 1 (Default: 84) • frequencies: mid-band [Hz] (Default: the eight octaves from 63 Hz)	apv = hearing.assumed_protection_value(grid) • AssumedProtectionResult (apv, mean_attenuation, standard_deviation, alpha, subjects)
octave_band_protected_level	function	Effective A-weighted level, octave-band method (ISO 4869-2 Formula (2)). • noise_levels: unweighted octave-band levels [dB] • apv: assumed protection values or the result carrying them • a_weighting: [dB] (Default: IEC 61672-1 Table 3)	res = hearing.octave_band_protected_level(noise, apv) • ProtectedLevelResult (effective_level, reported_level, noise_reduction, band_levels)
hml_rating / hml_protected_level	function	H, M and L values and their application (ISO 4869-2 Clause 7). • hml_rating(attenuation, performance=84): Formulae (3)-(15) over the eight reference noises of Table 2 • hml_protected_level(l_p_a, l_p_c, rating): Formulae (16)-(18), consuming the rounded triple	res = hearing.hml_protected_level(104.0, 103.0, hearing.hml_rating(grid)) • HMLRatingResult (high, medium, low, reported, subject_h/m/l, predicted_reduction)
snr_rating / snr_protected_level	function	Single number rating and its application (ISO 4869-2 Clause 8). • snr_rating(attenuation, performance=84): Formulae (19)-(22) against the pink noise of Table 3 • snr_protected_level(rating, l_p_c=...): Formula (23); or l_p_a= with c_minus_a= for Formula (24)	res = hearing.snr_protected_level(hearing.snr_rating(grid), l_p_c=103.0) • SNRRatingResult (snr, reported, subject_snr, mean, standard_deviation)
AssumedProtectionResult / HMLRatingResult / SNRRatingResult / ProtectedLevelResult	dataclass	ISO 4869-2 protector results. • Ratings expose the unrounded fit and reported, the integer the standard publishes • ProtectedLevelResult.reported_level rounds halves away from zero, not to even	apv = hearing.assumed_protection_value(grid)
PROTECTION_PERFORMANCES	dict	Table 1: the constant α for each protection performance x (ISO 4869-2). 50 → 0.00, 75 → 0.67, 80 → 0.84, 84 → 1.00, 90 → 1.28, 95 → 1.64, 98 → 2.00	hearing.PROTECTION_PERFORMANCES[84]
PROTECTOR_OCTAVE_BANDS / PROTECTOR_A_WEIGHTING	tuple	The eight octave bands of Formula (2) and frequency weighting A at them. 63 Hz to 8 kHz; the weighting is IEC 61672-1:2013 Table 3, which ISO 4869-2 reprints as its Table B.1	hearing.PROTECTOR_OCTAVE_BANDS
HML_REFERENCE_NOISES / HML_REFERENCE_C_MINUS_A / HML_REFERENCE_D	tuple	Table 2: the eight reference noises the HML method is fitted on. A-weighted octave-band levels 125 Hz to 8 kHz, their (LpC − LpA) and the empirical weights d	hearing.HML_REFERENCE_NOISES
active_insertion_loss	function	The active insertion loss of an ANR earmuff, its lower ear and its uncertainty (ISO 4869-6 5.4, 5.5 b) and Annex A). • passive_levels_db, active_levels_db: MIRE levels, (subjects, 2, bands) [dB], left ear first • or insertion_loss_db per ear, or already the lower ear • frequencies [Hz] (Default: the one-third octaves 50 Hz or 100 Hz to 10 kHz, or the octaves 63 Hz or 125 Hz to 8 kHz, by count)	ail = hearing.active_insertion_loss(passive_levels_db=off, active_levels_db=on) • ActiveInsertionLossResult
ActiveInsertionLossResult	dataclass	ISO 4869-6 active insertion loss. • insertion_loss_db (lower ear), per_ear_db • mean_db, standard_deviation_db, standard_uncertainty_db, expanded_uncertainty_db [dB] • .plot()	ail.expanded_uncertainty_db
anr_total_attenuation	function	Total attenuation of an ANR earmuff and its ISO 4869-2 ratings at 84 % (ISO 4869-6 5.5). • reat: ISO 4869-1 result or (subjects, octaves) grid, 63 Hz or 125 Hz to 8 kHz • insertion_loss: ActiveInsertionLossResult or a grid on the one-third octaves • passive side interpolated linearly in hertz, as ISO's calculation example does	anr = hearing.anr_total_attenuation(reat, ail) • AnrTotalAttenuationResult (total_octave_db, assumed_protection, hml, snr)
AnrTotalAttenuationResult	dataclass	ISO 4869-6 total attenuation. • total_octave_db (Formula (1)), total_third_octave_db, reat_third_octave_db, insertion_loss_db [dB] • assumed_protection, hml, snr at 84 % • .plot()	anr.hml.reported
assess_anr_linearity	function	Up to what external level does an ANR earmuff stay linear? (ISO 4869-6 5.4.4). • external_levels_db: 5 dB steps up to 110 dB • ear_levels_db: 125 Hz octave level at the ear, external levels on the last axis • or ear_third_octave_levels_db (100, 125, 160 Hz on the last axis)	hearing.assess_anr_linearity([90, 95, 100], ears).maximum_linear_level_db • AnrLinearityResult
AnrLinearityResult	dataclass	5.4.4 verdict. • maximum_linear_level_db, increments_db, linear per ear and step • passes, linear_to_110_db; no truth value • .plot()	lin.maximum_linear_level_db
ANR_WITHIN_LABORATORY_UNCERTAINTY	constant	Table A.2 of ISO 4869-6: the typical budget of the mean active insertion loss (0.6, 0.3, 0.4 dB) as a ProtectorUncertaintyBudget.	hearing.ANR_WITHIN_LABORATORY_UNCERTAINTY.expanded_db # 1.56
PINK_NOISE_A_WEIGHTED	tuple	Table 3: the pink noise the SNR method is defined against. A-weighted octave-band levels 125 Hz to 8 kHz of a pink noise whose C-weighted level is 100 dB	hearing.PINK_NOISE_A_WEIGHTED
INSTRUMENT_U2	mapping	Instrument standard uncertainty u2 [dB] (ISO 9612 Table C.5). Keyed by 'class1' (0.7), 'class2' (1.5), 'personal_exposimeter' (1.5)	INSTRUMENT_U2['class1'] # 0.7
OccupationalExposureWarning	warning class	ISO 9612 sampling advisory. Emitted for the 3 dB task spread (Clause 9.3), c₁u₁ > 3.5 dB (Clause 10.4) or a short Table 1 cumulative duration	warnings.simplefilter('error', OccupationalExposureWarning)
SoundPowerWarning	warning class	ISO 3744/3746/3741/9614-2/9295 qualification issue. Emitted when the background margin is below the criterion, K2 exceeds the validity limit, a band's power is negative, or the room fails qualification; levels are then upper bounds. Under ISO 9295 it is also emitted for a band outside the 16 kHz octave (11.2 kHz to 22.4 kHz), for a room constant taken from the air absorption below 10 kHz (clause 7.2), and for an FFT noise bandwidth wider than 112 Hz (clause 8.5.2)	warnings.simplefilter('error', SoundPowerWarning)
AbsorptionWarning	warning class	ISO 354 advisory. Emitted for a room below 150 m³, a sample area outside 10-12 m², an out-of-range temperature, or a non-physical α_s ≤ 0; the result still returns	warnings.simplefilter('error', AbsorptionWarning)
speech_intelligibility_index	function	Speech Intelligibility Index (ANSI S3.5-1997, any of its four band procedures). • speech_spectrum: equivalent speech spectrum levels [dB SPL] on the procedure's bands, or a vocal-effort name 'normal'/'raised'/'loud'/'shout' ('normal' only outside the one-third-octave procedure) • noise_spectrum: equivalent noise spectrum levels [dB SPL] (Default: None → quiet, −80 dB) • threshold: equivalent hearing threshold [dB HL] (Default: None → 0) • method: one of SII_METHODS (Default: 'one-third-octave') • band_importance: alternative Ii per band (Default: None → the procedure's table)	res = speech.speech_intelligibility_index("normal", noise_spectrum=[40.0]*18) • SIIResult; res.sii = 0.066
standard_speech_spectrum	function	Standard speech spectrum level by vocal effort (ANSI S3.5-1997 Table 3). • vocal_effort: 'normal', 'raised', 'loud' or 'shout' (Default: 'normal')	u = speech.standard_speech_spectrum('raised') • 18 band levels [dB SPL]
standard_speech_spectra	function	Plottable standard speech spectra by vocal effort (ANSI S3.5-1997 Table 3). • vocal_efforts: a name or sequence of 'normal'/'raised'/'loud'/'shout' (Default: the full family)	res = speech.standard_speech_spectra() • StandardSpeechSpectrum; res.plot()
StandardSpeechSpectrum	dataclass	Standard speech spectrum result. • frequencies: the 18 band centres [Hz] • vocal_efforts: the efforts carried • levels: Ui per effort, (len(vocal_efforts), 18) [dB SPL] • .plot(): the speech spectrum level vs one-third-octave band, one line per effort	res.levels, res.vocal_efforts
SIIResult	dataclass	SII result. • sii: index in [0, 1] • band_audibility: Ai per band (§5.8) • band_importance: Ii used • frequencies [Hz] • speech_spectrum / disturbance / masking: Ei′ / Di / Zi per band [dB] • level_distortion: Li per band (§5.7) • method: the band procedure used • .plot()	res.sii, res.band_audibility
SII_METHODS	constant	The four ANSI S3.5-1997 band procedures, in the order of its Tables 1 to 4. ('critical-band', 'equally-contributing', 'one-third-octave', 'octave'), i.e. 21, 17, 18 and 6 bands	for m in SII_METHODS: ...
sii_procedure	function	Tabulated band table of one ANSI S3.5-1997 band procedure (Tables 1–4). • method: one of SII_METHODS (Default: 'one-third-octave')	proc = speech.sii_procedure('octave') • SIIProcedure; proc.plot()
SIIProcedure	dataclass	ANSI S3.5-1997 band-procedure constants. • method: the procedure name • frequencies: nominal band centres [Hz] • band_edges: band limits [Hz], one more than the band count • band_importance: Ii • internal_noise: Xi [dB SPL] • speech_spectrum: Ui, normal vocal effort [dB SPL] • .plot(): Ii stepped over the band limits	proc.band_importance, proc.band_edges
stoi	function	Short-time objective intelligibility STOI / ESTOI (Taal et al. 2011; Jensen & Taal 2016). • clean: clean reference (1D) • degraded: degraded/processed signal (1D, same length) • fs [Hz] (resampled to 10 kHz internally) • extended: use ESTOI (Default: False)	d = speech.stoi(clean, degraded, fs) • STOIResult; d.value in ~[0, 1] (1 if identical)
STOIResult	dataclass	STOI / ESTOI result. • value: the intelligibility index • extended: True for ESTOI • segment_scores: per-segment intermediate • band_scores: per-band mean correlation (STOI; None for ESTOI) • band_frequencies [Hz] • fs (10 kHz) • .plot()	res.value, res.band_scores
thd	function	Total harmonic distortion (IEC 60268-3 14.12.2–3). • signal (1D), fs [Hz] • fundamental [Hz] (Default: None → largest peak) • kind: 'F' rel. fundamental or 'R' rel. total RMS (Default: 'F') • n_harmonics (Default: 10) • window (Default: 'hann')	thd(sig, fs, 1000.0, kind="F") • ratio (0..)
harmonic_distortion	function	nth-order harmonic distortion dₙ (IEC 60268-3 14.12.5). • signal, fs, fundamental [Hz], order n (≥ 2)	harmonic_distortion(sig, fs, fundamental=1000.0, order=2) • ratio (aₙ rel. total RMS)
thd_plus_noise	function	THD+N ratio (AES17-2015 6.3.1). • signal, fs, fundamental (Default: None) • notch_q: effective Q of the applied notch, 1.2–3 (Default: 2.0) • bandwidth: AES17 chain upper edge [Hz] (Default: 20000; None = full Nyquist); 20 Hz high-pass included • as_db: 20·lg(ratio) dB (Default: False) • window: FFT window for auto-detection (Default: 'hann')	thd_plus_noise(sig, fs, 1000.0) • ratio, or dB if as_db
sinad	function	Signal-to-noise-and-distortion ratio, dB (derived from AES17 THD+N). • signal, fs, fundamental (Default: None), notch_q (Default: 2.0), bandwidth (Default: 20000) = −(THD+N in dB)	sinad(sig, fs, 1000.0) • SINAD [dB]
dynamic_range	function	Dynamic range (AES17-2015 6.4.1), dB CCIR-RMS. • signal, fs, fundamental (Default: None → 997 Hz) • notch_q (Default: 2.0), bandwidth (Default: 20000) • full_scale: digital full-scale peak amplitude (Default: 1.0) = full-scale sine / CCIR-RMS-weighted notched residual	dynamic_range(out, fs, 997.0) • dB CCIR-RMS
idle_channel_noise	function	Idle channel noise level (AES17-2015 6.4.2), dBFS CCIR-RMS. • signal (idle output, 1D), fs • bandwidth (Default: 20000) • full_scale (Default: 1.0) = CCIR-RMS-weighted RMS re full scale	idle_channel_noise(idle, fs) • dBFS CCIR-RMS (−inf for digital zero)
weighted_thd	function	Weighted THD (IEC 60268-3 14.12.11). • signal, fs, fundamental (Default: None) • weighting: '468' (ITU-R BS.468-4 / IEC 60268-1, the 14.12.11 network), 'A' or 'C' (Default: '468') • notch_q (Default: 2.0) • valid for fundamentals 31.5–400 Hz	weighted_thd(sig, fs, 100.0) • ratio
itu_r_468_weighting	function	ITU-R BS.468-4 weighting response (clause 1, Fig. 1a). • frequencies [Hz] (≥ 0) • the Fig. 1a network evaluated in closed form, which Table 1 samples to 0.1 dB; DC → −inf	itu_r_468_weighting([6300.0]) # +12.2167 • dB re 1 kHz
modulation_distortion	function	Modulation distortion d_m,2 / d_m,3 (IEC 60268-3 14.12.7). • signal, fs, f_low [Hz], f_high [Hz] • arithmetic sideband sums over the f₂ amplitude (14.12.7.2 g–h)	modulation_distortion(sig, fs, f_low=60.0, f_high=7000.0).d2 • ModulationDistortionResult
ModulationDistortionResult	dataclass	Modulation distortion result. • d2 / d3: the IEC per-order values • smpte: combined-RMS analyzer convention (not an IEC quantity)	res.d2, res.d3, res.smpte
difference_frequency_distortion	function	Difference-frequency distortion d_d,n (IEC 60268-3 14.12.8). • signal, fs, f1 < f2 [Hz] • order: 2 or 3 (Default: 2) • ref. U₂,ref = 2·U₂,f₂; 3rd order sums arithmetically	difference_frequency_distortion(sig, fs, f1=13e3, f2=14e3, order=2) • ratio
total_difference_frequency_distortion	function	Total difference-frequency distortion (IEC 60268-3 14.12.10). • signal, fs • f1 (Default: 8000), f2 (Default: 11950) [Hz] = √(a²_{f₂−f₁} + a²_{2f₁−f₂}) / (a_{f₁} + a_{f₂})	total_difference_frequency_distortion(sig, fs) • ratio
dynamic_intermodulation_distortion	function	Dynamic intermodulation DIM (IEC 60268-3 14.12.9). • signal, fs • f_sine [Hz] (Default: 15000) • f_square [Hz] (Default: 3150)	dynamic_intermodulation_distortion(sig, fs) • ratio (products rel. 15 kHz sine)
harmonic_analysis	function	Full harmonic analysis (THD, THD+N, SINAD). • signal, fs, fundamental (Default: None) • n_harmonics (Default: 10), notch_q (Default: 2.0), bandwidth (Default: 20000) • window: FFT window (Default: 'hann')	res = electroacoustics.harmonic_analysis(sig, fs, 1000.0) • HarmonicDistortionResult
HarmonicDistortionResult	dataclass	Harmonic analysis result. • fundamental [Hz] • harmonic_frequencies / harmonic_amplitudes • thd_f / thd_r / thd_plus_noise: ratios • sinad_db [dB] • .plot(): annotated harmonic spectrum	res.thd_f, res.sinad_db
transfer_function	function	Frequency-response estimate H1/H2 (Bendat & Piersol). • x (input), y (output), fs [Hz] • estimator: 'H1' or 'H2' (Default: 'H1') • nperseg (Default: None), overlap (Default: 0.5)	res = electroacoustics.transfer_function(x, y, fs) • FrequencyResponseResult
coherence	function	Ordinary coherence γ² (Bendat & Piersol). • x, y, fs [Hz] • nperseg (Default: None), overlap (Default: 0.5) = |Gxy|²/(Gxx·Gyy) ∈ [0, 1]	f, g = electroacoustics.coherence(x, y, fs)
FrequencyResponseResult	dataclass	Frequency-response result. • frequencies [Hz] • response: complex H(f) • magnitude_db / phase [rad] • coherence: γ²(f) • estimator • .plot(): Bode + coherence	res.magnitude_db, res.coherence
synchronized_sweep_signal	function	Synchronized exponential sweep (Novak et al. 2015, Eqs. 47/49). • fs, f1 < f2 [Hz], seconds (quantized by the rounding) • amplitude (Default: 1.0), fade (Default: 0.0) Rate L = round(f1·T̃/ln(f2/f1))/f1 → f1·L integer, so a L·ln(n) shift equals the nth harmonic and harmonic phases become system properties	x = electroacoustics.synchronized_sweep_signal(48000, 20.0, 6000.0, 4.0) • sweep samples (duration L·ln(f2/f1))
swept_sine_distortion	function	Harmonic separation and THD(f) from one sweep (Farina 2000 / Novak et al. 2015). • recorded, fs, plus the generator parameters f1, f2, seconds • method: 'synchronized' (Default; analytic deconvolution, meaningful phases) / 'farina' (classical ESS, magnitudes only) • n_harmonics (Default: 5), ir_length (Default: largest power of two fitting the closest arrivals) • amplitude (Default: 1.0), fade (Default: generator default), remove_dc (Default: True)	res = electroacoustics.swept_sine_distortion(y, fs, 20.0, 6000.0, 4.0) • SweptSineDistortionResult
SweptSineDistortionResult	dataclass	Swept-sine harmonic separation. • frequencies [Hz], harmonic_responses: complex H₁..H_N, harmonic_irs (windowed, centred), delays L·ln(n) [s] • thd_frequencies [Hz], thd, distortion_ratios: |Hₙ(n·f)|/|H₁(f)| per order • fs, f1, f2, duration, rate L, method, n_harmonics • .plot(): |Hₙ| magnitudes + THD(f)	res.thd, res.harmonic_responses
radiating_piston	function	Radiation of a rigid baffled circular piston (Beranek & Mellow §4.19/§13.7). • radius a [m], frequencies [Hz] • speed_of_sound (Default: 343), density (Default: 1.206) • angles_rad: directivity polar angles_rad [rad] (Default: None)	res = electroacoustics.radiating_piston(0.1, freqs) • RadiatingPistonResult
plot_piston_geometry	function	Baffled piston to scale, optional far-field lobe. • radius a [m] • angles_rad [rad] + directivity (linear), together • lobe_label, language	plot_piston_geometry(0.1, angles_rad=ang, directivity=d) • Also RadiatingPistonResult.plot_geometry(frequency_index=...)
piston_resistance / piston_reactance	function	Normalized piston radiation impedance R1 = 1−2J1(x)/x, X1 = 2H1(x)/x, x = 2ka (Beranek & Mellow Eqs. 13.117/13.118).	piston_resistance(2.0) # 0.4233
piston_directivity	function	Far-field piston directivity 2·J1(ka·sinθ)/(ka·sinθ). • ka, theta [rad]	piston_directivity(5.0, 0.3)
piston_directivity_pattern	function	Far-field directivity (beam) pattern of one or more baffled pistons. • ka (scalar or 1-D) • angles_rad [rad] (Default: front hemisphere −90°…+90°)	p = electroacoustics.piston_directivity_pattern([3, 8, 16]) • PistonDirectivity
RadiatingPistonResult	dataclass	Piston radiation result. • ka, resistance/reactance, radiation_resistance/radiation_reactance [N·s/m], radiation_mass = 8ρa³/3 [kg], directivity_index [dB], directivity • .plot(): R1/X1 vs ka	res.radiation_mass
PistonDirectivity	dataclass	Piston directivity-pattern result. • angles_rad [rad], ka, directivity (linear), directivity_db • .plot(): polar beam pattern in dB (family over ka)	p.plot()
loudspeaker_characteristics	function	Rated loudspeaker characteristics for an IEC 60268-5 report. • frequencies, spl_db (on-axis SPL), rated_impedance R [Ω] • input_voltage (Default: √R → 1 W), distance (Default: 1 m), sensitivity_band, tolerance_db • impedance, distortion panels • directivity: LoudspeakerDirectivity (23), ratings: LoudspeakerRatings (18/19)	res = electroacoustics.loudspeaker_characteristics(f, spl, 8.0) • LoudspeakerCharacteristics
LoudspeakerDirectivity	dataclass	Directional characteristics of the loudspeaker (IEC 60268-5 Clause 23). • piston: a RadiatingPistonResult computed with angles_rad, or polar = (angles_deg, relative_db) • frequency [Hz], index_db (directivity index, 23.3)	LoudspeakerDirectivity(piston=res, frequency=2000.0)
LoudspeakerRatings	dataclass	Manufacturer-stated ratings (IEC 60268-5 Clauses 18 and 19). • frequency_range (lo, hi) [Hz] (19.1), also the band the 16.1 minimum impedance is scanned over • noise_power [W] (18.1), sinusoidal_power [W] (18.4), resonance_frequency [Hz] (19.2)	LoudspeakerRatings(frequency_range=(45.0, 22000.0))
LoudspeakerCharacteristics	dataclass	Loudspeaker rated-characteristics result (IEC 60268-5). • sensitivity_level_db (1 W/1 m, 20.3/20.4), effective_range (21.2), reference_level_db, characteristic_sensitivity_pa, minimum_impedance • .report(): IEC 60268-5 fiche (graphs to IEC 60263)	res.effective_range
feedback_stability	function	Gain before feedback of a reinforcement loop (Long, Architectural Acoustics 2e, Eqs. 18.16–18.24). • open_loop_gain Zs [dB] (≈ −6 in an auditorium) • level_loudspeaker_at_microphone L(H-M) [dB] • level_loudspeaker_at_listener L(H-L) [dB] • microphone_directivity DM(θ) [dB] (Default: 0) • open_microphones Nm (Default: 1), stability_margin [dB] (Default: 10)	res = electroacoustics.feedback_stability(-6.0, 76.0, 80.0) • FeedbackStabilityResult
FeedbackStabilityResult	dataclass	Gain structure and stability verdict. • open_loop_gain, feedback_loop_gain, nom_correction, loop_gain [dB] • margin, headroom, stability_margin [dB], is_stable • maximum_open_loop_gain, maximum_level_at_microphone [dB] • .plot(): gain bars against the oscillation and margin lines	res.is_stable, res.headroom res.plot()
feedback_loop_gain / open_microphone_correction	function	Feedback building blocks (Long Eqs. 18.18, 18.23). • feedback_loop_gain(L_HM, L_HL, microphone_directivity=0) = L(H-M) − L(H-L) + DM(θ) [dB] • open_microphone_correction(Nm) = 10 lg Nm [dB]	open_microphone_correction(4) # 6.02
plot_sound_reinforcement_geometry	function	Schematic of the feedback loop with each path length annotated. • talker_distance, microphone_distance, listener_distance [m] • language	plot_sound_reinforcement_geometry(0.3, 4.0, 12.0)
DEFAULT_STABILITY_MARGIN / CARDIOID_RELATIVE_DIRECTIVITY	constant	Reinforcement defaults (Long Ch. 18). • 10 dB feedback stability margin for an equalised system • −2 dB cardioid directivity toward the loudspeaker relative to the talker	feedback_stability(-6.0, 78.0, 80.0, microphone_directivity=CARDIOID_RELATIVE_DIRECTIVITY)
microphone_characteristics	function	Rated microphone characteristics for an IEC 60268-4 report. • frequencies, response_db (free-field, re the reference frequency), sensitivity_mv_per_pa M [mV/Pa] • reference_frequency (Default: 1 kHz), tolerance_db (Default: 2) • directivity: MicrophoneDirectivity (13), noise: MicrophoneNoise (17), overload: MicrophoneOverload (14.2/15.2), electrical: MicrophoneElectrical (9/10)	res = electroacoustics.microphone_characteristics(f, resp, 12.5) • MicrophoneCharacteristics
MicrophoneDirectivity	dataclass	Directional characteristics of the microphone (IEC 60268-4 Clause 13). • polar = (angles_deg, relative_db) (13.1) • frequency [Hz], index_db (directivity index, 13.2; computed from polar when omitted)	MicrophoneDirectivity(polar=(ang, cardioid), frequency=1000.0)
MicrophoneNoise	dataclass	Inherent noise of the microphone (IEC 60268-4 Clause 17). • voltage U_N [V] (17.2 b) or equivalent_level_db [dB SPL] (17.1), not both • weighting: "A" (Default) or "468", the ITU-R BS.468-4 quasi-peak figure; spectrum = (frequencies, band_levels_db)	MicrophoneNoise(voltage=1.25e-6)
MicrophoneOverload	dataclass	Overload sound pressure and the distortion it is read from (IEC 60268-4 14.2/15.2). • distortion = (spl_db, thd_percent) (14.2) • thd_percent limit (Default: 1), spl_db (stated overload level; read off the curve when omitted)	MicrophoneOverload(distortion=(spl, thd), thd_percent=0.5)
MicrophoneElectrical	dataclass	Electrical impedance and rated power supply (IEC 60268-4 Clauses 10/9). • rated_impedance [Ω] (10.2), minimum_load_impedance [Ω] (10.3) • powering (9.1), supply_current_ma [mA] (9.1)	MicrophoneElectrical(rated_impedance=150.0, powering="Phantom P48 (IEC 61938)")
MicrophoneCharacteristics	dataclass	Microphone rated-characteristics result (IEC 60268-4). • sensitivity_level_db = 20·lg(M / 1 V/Pa) (11.1), effective_range (12.2), directivity_index_db (13.2.2), equivalent_noise_level_db (17.2), max_spl_db (15.2), signal_to_noise_ratio_db, diffuse_field_sensitivity_level_db • .report(): IEC 60268-4 fiche (graphs to IEC 60263)	res.sensitivity_level_db
expansion_chamber	function	Expansion-chamber silencer TL/IL (Bies Eq. 8.111, four-pole). • frequencies, length L, chamber_area, pipe_area • source_impedance/radiation_impedance (Default: None → no IL)	res = noise_control.expansion_chamber(f, 0.3, 0.04, 0.01) • ReactiveSilencerResult
plot_silencer_geometry	function	To-scale silencer cross-section. • kind: the ReactiveSilencerResult.kind strings • Chamber: length, chamber_area, pipe_area (+ inlet_extension/outlet_extension) • Branch: duct_area + Helmholtz (neck_area, neck_length, cavity_volume) or quarter-wave (length, branch_area) • language	plot_silencer_geometry('expansion chamber', length=0.3, chamber_area=0.03, pipe_area=0.005) • Equivalent circular diameters 2·√(S/π); also ReactiveSilencerResult.plot_geometry()
helmholtz_resonator / quarter_wave_resonator	function	Side-branch resonator silencers (Bies Eqs. 8.46/8.44). • Helmholtz: duct_area, neck_area, neck_length, cavity_volume • Quarter-wave: duct_area, length, branch_area	quarter_wave_resonator(f, 0.01, 1.5, 2e-3)
extended_tube_chamber	function	Extended-inlet/outlet expansion chamber (Bies §8.9.7); reduces to expansion_chamber at zero extension. • length, chamber_area, pipe_area, inlet_extension, outlet_extension	extended_tube_chamber(f, 0.4, 0.04, 0.01, inlet_extension=0.1)
transmission_loss	function	Transmission loss of a four-pole element (Munjal Eq. (3.27), no flow). • transfer_matrix T, shape (n_freq, 2, 2) • inlet_area S_in / outlet_area S_out [m²] • speed_of_sound / density • The anechoic termination is part of the definition, so this describes the element alone	transmission_loss(t, inlet_area=0.01, outlet_area=0.01)
insertion_loss	function	Insertion loss of a four-pole element for stated end impedances. • transfer_matrix T • source_impedance Z_s, radiation_impedance Z_r [Pa·s/m³] • Unlike the transmission loss it depends on the source and the termination, which is what makes it the number a client hears	insertion_loss(t, source_impedance=zs, radiation_impedance=zr)
duct_matrix / shunt_matrix / cascade	function	The four-pole primitives the silencers are assembled from (Bies Eqs. 8.143/8.144). • duct_matrix(frequencies, length, area, ...): a straight duct • shunt_matrix(branch_impedance): a side branch of impedance Z_b • cascade(*matrices): multiplies elements inlet to outlet	t = noise_control.cascade(noise_control.duct_matrix(f, 0.1, s), noise_control.shunt_matrix(z))
helmholtz_impedance / quarter_wave_impedance	function	Side-branch impedances to feed shunt_matrix (Bies Eqs. 8.152/8.146). • Helmholtz: neck_area, neck_length, cavity_volume, resistance • Quarter-wave: length, area • speed_of_sound / density	shunt_matrix(noise_control.helmholtz_impedance(f, 1e-3, 0.05, 2e-3))
ReactiveSilencerResult	dataclass	Reactive-silencer result. • frequencies, transmission_loss, insertion_loss (or None), transfer_matrix, kind, resonances • .plot(): TL/IL vs frequency	res.transmission_loss
SilencerChain	class	Hand-built four-pole chain that keeps the geometry it was given. • SilencerChain(frequencies, speed_of_sound=…, density=…) • .duct(length, area) and .shunt(branch_impedance, label=…) in order, each returning the chain • .transfer_matrix, .result(inlet_area=…, outlet_area=…), .plot_geometry()	SilencerChain(f).duct(0.3, 0.031).shunt(zb).duct(0.6, 0.126) • Ducts drawn to scale, shunts marked as branch points
SilencerChainElement	dataclass	One recorded element of a SilencerChain. • matrix, plus whatever geometry the call was handed: length and area for a duct, neither for a shunt • label, shorting_frequency (where the branch impedance is least), .is_duct	chain.elements[0].area
substitution_insertion_loss	function	The measured insertion loss of ISO 7235 Eq. (1) and ISO 11691 Eq. (1): the level without the silencer minus the level with it. • substitution_level (the series run with the substitution duct), object_level (the series run with the test object) [dB] • reverberation_times: optionally (T_1, T_2) [s], adding the 10 lg(T_2/T_1) of ISO 7235 6.3; one value stands for every band • the two standards number the series the opposite way round; the argument names are neither numbering	noise_control.substitution_insertion_loss(sub, obj)
octave_insertion_loss	function	ISO 11691 Eq. (2): three one-third octaves folded into their octave on the transmitted energy. • insertion_loss [dB], a multiple of three bands in ascending order • -10 lg[(10^-D1/10 + 10^-D2/10 + 10^-D3/10)/3], so the leakiest third decides the octave: 30, 30 and 5 dB give 9.7 dB, not 21.7	noise_control.octave_insertion_loss([30.0, 30.0, 5.0]) # 9.744
microphone_spread_limit / microphone_positions_required / ISO7235_SPREAD_LIMITS	function / function / constant	ISO 7235 Table 6 and the rule of 6.2.1 it serves: when three microphone positions in a test duct are not enough. • microphone_spread_limit(frequency): 10 dB at 50 and 63 Hz, 8 at 80 and 100, 7 at 125, 6 from 160 up • microphone_positions_required(levels, frequency): 3 or 5, from the spread of exactly three levels • the printed last row says > 160, leaving the 160 Hz band with no limit; read here as 160 and above (see the errata)	noise_control.microphone_positions_required([70.0, 74.0, 79.0], 125.0) # 5
measurement_reproducibility / measurement_expanded_uncertainty / ISO7235_REPRODUCIBILITY / ISO7235_COVERAGE_FACTOR	function / function / table / constant	ISO 7235 Table 7 and 7.9: how repeatable the measurement is, and the uncertainty that goes on the report. • frequency [Hz], quantity: 'insertion_loss' (Default), 'transmission_loss' or 'intensity' • insertion loss 1.5/1/2/3 dB by band range, transmission loss a flat 3, intensity 3/1.5/1/1 and stopping at 5 kHz • the expanded uncertainty is ISO7235_COVERAGE_FACTOR = 2 times the deviation, for 95 % coverage	noise_control.measurement_expanded_uncertainty(4000.0) # 6.0 dB
survey_reproducibility / ISO11691_REPRODUCIBILITY	function / constant	ISO 11691 Table 1: 2 dB up to the 1.25 kHz one-third octave and 3 dB above it. • frequency [Hz] • the standard offers no interlaboratory result of its own and says this estimate is what makes it a survey method	noise_control.survey_reproducibility(1000.0) # 2.0 dB
substitution_area_ratio / SURVEY_AREA_RATIO_RANGE / SURVEY_MAX_VELOCITY_M_S / SURVEY_DIAMETER_RANGE_M / SURVEY_BAND_RANGE_HZ / SilencerMeasurementWarning	function / range / constant / range / range / warning class	The scope ISO 11691 writes for its own survey method. • substitution_area_ratio(duct_area, element_area) [m²], warning outside the 0.6 to 1.7 of 4.5 • design velocity up to 15 m/s (1.1), circular diameters 80 mm to 2 m, one-third octaves from 50 Hz to 10 kHz	noise_control.substitution_area_ratio(0.09, 0.09) # 1.0 Emitted by noise_control.silencer_measurement
open_end_transmission_loss / open_end_reflection_coefficient / RADIATION_SOLID_ANGLES	function / function / mapping	ISO 7235 Eqs. (B.3) and (B.4): what the open end of a duct keeps in, and the reflection that is the same fact said the other way. • frequency [Hz], area S [m²], solid_angle_sr Ω [sr] (Default: 2π), speed_of_sound [m/s] • D_td = 10 lg[1 + Ω/(4πf√S/c)²], r = [(1/Ω)(4πf√S/c)² + 1]^(−1/2), and the two close through D_td = −10 lg(1 − r²) • RADIATION_SOLID_ANGLES is Table B.1, the same five values as ISO 5135 Table 1: A 2π, B π, C 4π, D 2π, E 4π • the same physics as end_reflection_loss_closed_form, which raises the same argument to 1.88 rather than to 2	noise_control.open_end_transmission_loss(bands, 0.0962)
measured_transmission_loss / flow_noise_power_level	function	ISO 7235 Eqs. (6) and (7): the two quantities the open-end loss is needed for. • measured_transmission_loss(insertion_loss, open_end_loss): D_t = D_i + D_td, the transmission loss of an air-terminal unit • flow_noise_power_level(pressure_level, open_end_loss, room_correction): L_W = L_p + D_td + C, with L_p uncorrected for background as 6.4 requires and C from ISO 3741	noise_control.measured_transmission_loss(d_i, d_td)
modal_filter_cut_on / CIRCULAR_CUT_ON_COEFFICIENT / RECTANGULAR_CUT_ON_COEFFICIENT / MODAL_FILTER_ATTENUATION_DB	function / constant / constant / constant	ISO 7235 Eqs. (4) and (5): where higher-order modes start in the duct the modal filter is connected to. • exactly one of diameter_m d or larger_dimension H [m], plus speed_of_sound • 0.59 c/d and 0.5 c/H; the rectangular constant is exact, the circular one sits 0.67 % above the Bessel eigenvalue that circular_duct_cut_on uses • MODAL_FILTER_ATTENUATION_DB = (3.0, 5.0), the minimum longitudinal attenuation of 5.2.2.3 below and above it	noise_control.modal_filter_cut_on(diameter_m=0.4) # 506 Hz
normal_air_density / ISO7235_GAS_CONSTANT / ISO7235_ABSOLUTE_ZERO_OFFSET	function / constant / constant	ISO 7235 Eqs. (10), (21) and (22): the gas law with the standard's own two constants. • static_gauge_pressure_pa p_s1 [Pa, relative to ambient], ambient_pressure_pa p_a [Pa absolute], temperature_c θ [°C] • R = 287 and θ + 273, both as printed rather than 287.05 and 273.15; together 0.069 % high at 20 °C, and both cancel in the pressure loss coefficient	noise_control.normal_air_density(200.0, 101325.0, 20.0) # 1.2073
volume_flow_rate / dynamic_pressure / total_pressure / DENSITY_RATIO_RANGE	function / function / function / constant	ISO 7235 Eqs. (8), (9), (11), (13), (16), (19) and (20): the flow quantities the pressure loss coefficient is built from. • volume_flow_rate(mass_flow, density): q_V = q_m/ρ, with ρ the normalised density of Eq. (10) when the meter and the object leave DENSITY_RATIO_RANGE (0.98 to 1.02) • dynamic_pressure(volume_flow, area, density): (ρ/2)(q_V/S)², the velocity head • total_pressure(static_pressure, volume_flow, area, density): static plus dynamic in one plane	noise_control.dynamic_pressure(1.0, 0.0962, 1.2) # 64.8 Pa
total_pressure_loss / pressure_loss_coefficient / average_pressure_loss_coefficient	function	ISO 7235 Eqs. (12), (14), (17) and (18): what an object costs to push air through, in velocity heads. • total_pressure_loss(static_pressure_loss_pa, inlet_dynamic_pressure_pa, inlet_area, outlet_area): adds p_d1[1 − (S_1/S_2)²], which vanishes when the two ducts match • pressure_loss_coefficient(total_loss, inlet_dynamic_pressure_pa): ζ, the same number at every flow rate the object sees the same flow pattern at, warning at 10 Pa and below • average_pressure_loss_coefficient(object_static, object_dynamic, substitution_static, substitution_dynamic): Eq. (18), a substitution average over each series' own flow rates, warning below five points	noise_control.pressure_loss_coefficient(45.0, 64.8) # 0.694
upstream_straight_length / MINIMUM_FLOW_RATES / MINIMUM_PRESSURE_DIFFERENCE_PA / UPSTREAM_STRAIGHT_DIAMETERS / UPSTREAM_STRAIGHT_MIN_M / VELOCITY_PROFILE_TOLERANCE_PERCENT	function / constant	ISO 7235 6.5.2.1 and 6.5.2.2.1: what a flow measurement needs before it counts. • upstream_straight_length(area): max(5 d_e, 2 m) with d_e = √(4S/π), the two rules crossing at a 0.4 m equivalent diameter • five airflow rates per series, the lowest above 10 Pa, and a velocity profile uniform to ±10 % excluding 15 mm from the walls	noise_control.upstream_straight_length(0.5) # 3.99 m
duct_sound_power_level	function	ISO 5135 Eq. (1): from what the room heard back to what the duct carries. • room_sound_power_level L_W [dB] from ISO 3741, end_reflection_loss ΔL_r [dB] • ISO 5135 Eq. (2) is ISO 7235 Eq. (B.3) written out, so open_end_transmission_loss supplies both, and their two solid-angle tables agree entry for entry • the NOTE to Table 1 offers a transmission element to ISO 7235 as an alternative to correcting at all	noise_control.duct_sound_power_level(lw, d_td)
fit_operating_line / OperatingLine / EXTRAPOLATION_MAX_DEVIATION_DB / EXTRAPOLATION_RANGE_FACTORS / REPORTING_RESOLUTION_DB	function / dataclass / constant	ISO 5135 5.5.2: the least-squares line a level is read off at a duty the laboratory did not measure at. • duty q_V [m³/s] or Δp_t [Pa], levels [dB], at least two points at more than one duty • result: slope [dB/decade], intercept, maximum_deviation, smallest_duty, largest_duty, valid_range (half to twice), .level_at(duty), .plot() • warns past the 3 dB of 5.5.2, and again when a duty is read outside the range the clause allows; 8 k) reports to half a decibel	noise_control.fit_operating_line(q, lwa).level_at(0.3)
end_reflection_loss / elbow_insertion_loss	function	HVAC duct end reflection & bend insertion loss (Bies Tables 8.14/8.11, ASHRAE). • end: frequencies, diameter_m, termination 'flush'/'free' • elbow: frequencies, width, bend_type, vanes, lined	end_reflection_loss(bands, 0.3) • HvacSpectrumResult
plenum_attenuation	function	Plenum-chamber TL by Wells' method (Bies Eq. 8.275). • exit_area, line_of_sight, wall_area, mean_absorption, angle_rad	plenum_attenuation(0.1, 1.0, 20.0, 0.2) # dB
plot_plenum_geometry	function	Plenum section honouring r and θ exactly. • exit_area S_out [m²], line_of_sight r [m], wall_area S_w [m²] • angle_rad θ [rad] (Default: 0) • language	plot_plenum_geometry(0.09, 1.2, 6.0, angle_rad=0.35) • Box fixed by r/θ, S_out mouth to scale, S_w annotated
flow_noise_straight_duct / flow_noise_bend	function	HVAC flow-generated (self) noise sound power (VDI 2081, Bies Eqs. 8.251/8.254). • frequencies, flow_velocity, area (+ height for the bend)	flow_noise_straight_duct(bands, 10.0, 0.04) • HvacSpectrumResult
flow_noise_straight_duct_overall	function	Overall flow noise of a straight run (VDI 2081 Equations (16) and (17)). • flow_velocity v, area S • weighting='Z' gives 7 + 50 lg v + 10 lg S, 'A' gives -25 + 70 lg v + 10 lg S • the octave levels of flow_noise_straight_duct do not sum back to it: Figure 16 is a shape, not a partition	flow_noise_straight_duct_overall(5.83, 0.2) • 38.3
HvacSpectrumResult	dataclass	Per-frequency HVAC attenuation or regenerated Lw. • frequencies, values, quantity, label • .plot()	res.values
fan_sound_power	function	Octave-band fan sound power from the operating point, by either method (Long Eq. 13.1 / ASHRAE 1987, or VDI 2081 Blatt 1 Eqs. (13)/(15)). • model: 'ashrae' (Default) or 'vdi2081'; each takes its own arguments, and the two pressures are different quantities • volume_flow Q [m³/s] • ASHRAE: fan_static_pressure_pa P [Pa gauge] • fan_type (Table 13.5 rows: 'forward_curved', 'airfoil_large', 'radial_high', 'vaneaxial_hub_low', 'tubeaxial_small', 'propeller' …) • relative_efficiency_percent [% of peak] (Default: 80 → C_EFF 6 dB), blade_frequency • VDI 2081: fan_total_pressure_pa Δp_t [Pa], assembly ('rr'/'t'/'am'), fan_speed_rpm n [min⁻¹], specific_sound_power_level L_WSM (Default: 34/36/42 dB by assembly), blade_count z, relative_flow V̇/V̇_opt (Default: 1) • frequencies	fan_sound_power(2.36, fan_static_pressure_pa=498.0) • HvacSpectrumResult; prefer AMCA 300 manufacturer data
octave_band_limits / VDI2081_SPECTRAL_CORRECTION	function / array	Octave limits from an A-weighted room requirement (VDI 2081 Blatt 2 Eq. (1)). • a_weighted_limit_db L_A [dB], frequencies • L_Okt,max = L_A + K_A, with K_A the inverse A-weighting less the 5 dB the guideline allows for the sum of eight octaves • VDI2081_SPECTRAL_CORRECTION: K_A = 21, 11, 4, −2, −5, −6, −6, −4 dB	noise_control.octave_band_limits(25.0) • HvacSpectrumResult (46, 36, 29, 23, 20, 19, 19, 21 dB)
fan_efficiency_correction / blade_passing_frequency / fan_casing_attenuation	function	The three side terms of the fan model (Long Tables 13.6/13.7/13.8, Eq. 13.4). • fan_efficiency_correction(relative_efficiency_percent=80.0) → C_EFF [dB] (6,0 at 80 %) • blade_passing_frequency(rotational_speed, blades) = rpm·N/60 [Hz] • fan_casing_attenuation(frequencies) → casing-radiated attenuation	blade_passing_frequency(1200.0, 12) # 240 Hz
HvacWarning	warning class	A relative efficiency below the 50 % floor Long Table 13.6 is tabulated from. The table's worst-case row is returned, which is where a caller who passed a fraction such as 0,8 instead of 80 also lands; the two are indistinguishable from the value alone	warnings.simplefilter("error", noise_control.HvacWarning) Emitted by noise_control.hvac
unlined_rectangular_duct_attenuation / unlined_circular_duct_attenuation	function	Straight unlined sheet-metal duct attenuation (Long Eqs. 14.9-14.11, Table 14.1). • rectangular: frequencies, width, height, length, wrapped (fibreglass blanket doubles 63-250 Hz) • circular: frequencies, length (about a tenth of the rectangular loss)	unlined_rectangular_duct_attenuation(bands, 0.9, 0.6, 1.5) • HvacSpectrumResult
lined_rectangular_duct_attenuation / lined_circular_duct_attenuation	function	Lined-duct insertion loss, Reynolds (1990) regressions (Long Eqs. 14.12/14.13, Tables 14.2/14.3). • rectangular: frequencies, width, height, length, lining_thickness, include_unlined • circular: frequencies, diameter_m, length, lining_thickness • Flanking caps a run at 40 dB	lined_rectangular_duct_attenuation(None, 0.46, 0.30, 1.8, 0.025)
flexible_duct_insertion_loss	function	Lined round flexible duct IL (Long Table 14.4, ASHRAE 1995), 63 Hz-4 kHz. • frequencies, diameter_m (100-406 mm), length (0.9-3.7 m) • Interpolated over length and log diameter_m	flexible_duct_insertion_loss(None, 0.305, 1.8)
splitter_silencer_insertion_loss	function	Parallel-splitter (dissipative) silencer IL: each airway a lined duct of half the splitter thickness, combined by Bies Eq. (8.241). • frequencies, height, length, airway_widths (scalar or per airway), splitter_thickness • Prefer the manufacturer's dynamic insertion loss	splitter_silencer_insertion_loss(None, 0.6, 1.5, [0.1]*3, 0.2)
silencer_self_noise	function	Regenerated (self) noise of a splitter silencer (Long Eq. 14.31 + Table 14.8, Fry 1988). • frequencies, airway_velocity V [m/s], passages N, height H [m] L_W = 55·lg V + 10·lg N + 10·lg(H/1 mm) − 45	silencer_self_noise(None, 10.0, 4, 0.9)
section_change_loss	function	Reflection at a sudden change of duct section (VDI 2081 6.3, Figure 26). • upstream_area S1, downstream_area S2; the loss is 10 lg (r+1)²/(4r) in r = S1/S2 • a sudden reduction reflects in every band; a sudden increase only below the limit frequency of the upstream duct, so shape and upstream_size are needed for it • cap (Default: 5 dB, VDI 3733's recommendation)	noise_control.section_change_loss(bands, 0.5, 0.2, shape='round') • 0.88 dB
split_loss	function	Branch power-division loss at a duct split (Long Eq. 14.17), returned as a positive attenuation. • main_area S_m [m²], branch_areas [m²], branch index	split_loss(0.6, [0.15]*4) # 6.02 dB
end_reflection_loss_closed_form / equivalent_diameter	function	Reynolds' closed-form duct end reflection (Long Eqs. 14.14-14.16); the alternative to the end_reflection_loss table look-up (method='long'). • frequencies, diameter_m, termination 'flush'/'free' • equivalent_diameter(area) = √(4S/π) for a rectangular duct	end_reflection_loss(bands, 0.3, method='long')
diffuser_sound_power	function	Regenerated (self) noise of a grille, register or diffuser (Long Eqs. 13.27-13.33, Reynolds 1990). • frequencies, face_area S_G [m²], volume_flow Q [m³/s], pressure_drop_pa ΔP [Pa] • shape 'rectangular'/'round', count n (adds 10·lg n) • 18 dB per doubling of approach velocity; peak band at f_P = 48.8·U_G	diffuser_sound_power(None, 0.372, 0.147, 12.4)
air_terminal_velocity_limit / air_terminal_damper_correction	function	Screening checks for grilles, registers and diffusers (ASHRAE 2019 Ch. 49 Tables 9/10); a measured device spectrum to ASHRAE Standard 70 beats both. • air_terminal_velocity_limit(design_criterion, opening='supply'/'return') [m/s] • air_terminal_damper_correction(pressure_ratio, location='diffuser_neck'/'plenum_inlet'/'supply_duct') [dB]	air_terminal_velocity_limit(30) # 2.2 m/s
room_effect	function	Room effect: the drop from the sound power at the terminal device to the level in the room (Long Eq. 14.40, VDI 2081-1 Eq. 36), as a positive attenuation. • distance r [m] • room_constant R [m²] or absorption_area A [m²], exactly one, scalar or per band • directivity Q (Default: 2, flush in a ceiling), scalar or per band	room_effect(3.0, room.room_constant(S, alpha)) room_effect(1.5, absorption_area=20.0, directivity=q_per_band)
duct_path	function	End-to-end duct-borne cascade, fan to room (Long Table 14.9; AHRI 885 Table 8). • frequencies, source_level L_W, elements (DuctElement list) • room_effect, criterion 'NC'/'RC', target, self_noise_floor (Default: 0 dB) • section/flow_velocity → plane-wave validity warning	duct_path(bands, lw, elements, room_effect=6.0, target=30) • DuctPathResult
DuctElement / DuctPathStage	dataclass	One path element and its computed rows. • DuctElement: label, attenuation (positive loss; scalar, array or HvacSpectrumResult), self_noise L_W, code • DuctPathStage: attenuation, attenuated (the Sum row), self_noise, levels (the Combined row)	DuctElement('Silencer', il, sn, code='3')
DuctPathResult	dataclass	Duct-borne noise path result. • received_level, stages, room_effect, criterion, target, contributions • .rating (NC/RC), .criterion_curve, .exceedance, .meets_target • .table(): the printed sheet, row by row • .plot(): the cascade vs the criterion curve; .report(): one-page sheet	res.meets_target
combine_duct_paths	function	Energy sum of the received spectra of several paths (supply + return). • paths, criterion, target, label	combine_duct_paths([supply, ret]) • DuctPathResult with contributions
room_to_room_transmission	function	Room-to-room chain: source-room level → partition TL → receiving-room absorption → criterion (Norton Eq. 4.101, NR = TL − 10 lg[S_w/(S₂α₂ + τS_w)]). • frequencies, transmission_loss, partition_area S_w [m²], receiving_absorption S₂α₂ [m²] • source: SourceRoom • include_partition_transmission (the τS_w term) • criterion: DesignCriterion, label • receiver_distance_m [m]: adds the direct field of the partition at that distance, Barron (2003) Eqs. (7-71) and (7-72), g = 1/4 inside r* = (S_w/2π)^½ and S_w/(8πr₂²) beyond it; None (Default) is the reverberant field alone	room_to_room_transmission(bands, tl, 24.0, a2, source=noise_control.SourceRoom(level=lp1), criterion=noise_control.DesignCriterion(target=45)) • RoomToRoomResult
RoomToRoomResult	dataclass	Room-to-room chain result. • source_level, transmission_loss, receiving_absorption, noise_reduction, received_level • .rating (NC/RC), .criterion_curve, .exceedance, .meets_target • .required_transmission_loss: the partition TL that just meets the criterion, at receiver_distance_m when one was given • .table(): the rows of the hand calculation; .plot(): both spectra, the curve and NR	res.required_transmission_loss
SourceRoom	dataclass	The source room of the room-to-room chain (Norton 4.7, Table 4.5). • level L_p1 [dB], or power_level L_W [dB] + room_constant R₁ [m²] • directivity Q (Default: 1) • model: 'constant_power' (Default) / 'constant_volume' / 'constant_pressure'	SourceRoom(power_level=lw, room_constant=r1, directivity=4.0, model='constant_volume')
DesignCriterion	dataclass	The design criterion of a composed chain. • family: 'NC' (Default) / 'RC' • target (Default: None → no verdict) • flanking_penalty [dB] (Default: 0)	DesignCriterion(target=45.0, flanking_penalty=3.0)
circular_duct_cut_on / rectangular_duct_cut_on	function	Higher-order acoustic mode cut-on with mean flow (Norton & Karczub Eqs. 7.6-7.10, Table 7.1). • circular: diameter_m, flow_velocity, speed_of_sound, count (≤ 12) • rectangular: width, height, … • Flow lowers every cut-on by √(1 − M²) and shifts it to k_x = −Mκ/√(1 − M²)	circular_duct_cut_on(0.254, flow_velocity=200.0) • DuctModeResult
DuctModeResult	dataclass	Duct cut-on result. • modes (p, q), cut_on, cut_on_no_flow, axial_wavenumber, mach • .plane_wave_limit: the lowest cut-on • .plot(): the cut-on ladder with and without flow	res.plane_wave_limit
plane_wave_limit / PlaneWaveWarning	function / warning class	The frequency above which a duct stops carrying plane waves only, and the warning the plane-wave results raise past it. • plane_wave_limit(diameter_m=…), or width/height, or area • flow_velocity, speed_of_sound • Emitted by duct_path(section=…) and by every ReactiveSilencerResult	plane_wave_limit(width=0.65, height=0.4) # 264 Hz
DuctWallSpectrum	dataclass	One duct wall of one printed table, in one of the two directions. • transmission_loss_63_db … transmission_loss_8000_db, in decibels, and direction says whether they are the sound leaving the duct or the sound entering it • shape: what the table's own title calls the duct, 'rectangular', 'round', 'flat oval' or 'circular'; the chapter uses two words for one geometry • first_side_mm / second_side_mm in the order the page prints them, or diameter_mm, and duct_length_m for the two tables that print a length per row • sheet_metal_gauge: the US gauge exactly as printed, asterisk and all; the chapter converts one of the six these tables use, '16 ga (1.6 mm thickness)' on folio 49.37, and none of the other five, so no thickness is offered • .is_breakout, .is_break_in, .bands(), .spectrum() → {band_hz: db}, .transmission_loss_db(band_hz) narrows or refuses • ranges + bounded_below for a cell written >45, whose open end is empty because a transmission loss has no ceiling, and unquantified for one printed as a rule the chapter never explains; a value the page puts in parentheses is held as printed and the mark is recorded in note	row = noise_control.duct_wall_named('305 × 305 mm')[0] row.direction # 'breakout' row.transmission_loss_db(63) # 21 dB • PUBLISHED_DUCT_TRANSMISSION_LOSS, duct_wall_named
PUBLISHED_DUCT_TRANSMISSION_LOSS	mapping	Forty-six duct walls over six published tables, keyed '<table>/<row>'. • ASHRAE Chapter 49 Tables 29 to 34 (PDF pages 914-916): breakout for rectangular, round and flat oval ducts, then break-in for the same three • one row per printed row and one quantity per row: the round tables measure 200, 350, 560 and 810 mm at 4.6 m for breakout and 203, 356, 559 and 813 mm at 4.57 m for break-in, so there is no construction that carries both • only the two measured tables say so in their titles, and they are the two that carry the bounds and the parenthesised values the background sound left; the other four say nothing about how they were obtained • no table carries a source line, and every row credits the sentence of running text that credits it, in attributed_to['table'] • machine equipment room walls are not here: Table 40 of the same chapter is an ordinary partition and is published from building.PUBLISHED_TRANSMISSION_LOSS	noise_control.PUBLISHED_DUCT_TRANSMISSION_LOSS['ashrae-2019-tables-29-to-34/t30_long_seam_200_gage_26'] • DuctWallSpectrum, duct_wall_named
duct_wall_named	function	Every duct wall whose printed label contains the text. • name: part of a row label with the unit its column heading carries, '610 mm', '305 × 1220', matched without case • one size is printed by a breakout table and by a break-in table, so the plain answer is two rows that are two different quantities; read direction to tell them apart	noise_control.duct_wall_named('305 × 305 mm') # two rows, two quantities • PUBLISHED_DUCT_TRANSMISSION_LOSS
DUCT_WALL_BANDS_HZ	constant	The octave bands a duct-wall table can print: 63 Hz to 8 kHz. • (63, 125, 250, 500, 1000, 2000, 4000, 8000); the two rectangular tables print all eight, and the round, circular and flat oval ones stop at 4 kHz and leave the last field empty on every row	noise_control.DUCT_WALL_BANDS_HZ[-1] # 8000
enclosure_insertion_loss / ENCLOSURE_MODELS	function / mapping	Machine-enclosure insertion loss IL = R − C (Bies Eqs. 7.103/7.111); panel R supplied by the caller, never predicted. • panel_transmission_loss (per-band array or callable of f) • external_area, internal_area, internal_absorption • frequencies (required for a callable R) • model: ENCLOSURE_MODELS ('bies' keeps the 0.3 floor of Eq. 7.111, 'norton' the bare C = 10 lg(S_E/R_i) of Eq. 4.115)	enclosure_insertion_loss(R, 6.0, 5.0, 0.3) • EnclosureResult
enclosure_required_transmission_loss	function	The same equation solved for the panel R: R = IL + C (Norton Eq. 4.115 design use). • insertion_loss (required IL per band, e.g. the room level minus an NC curve) • external_area, internal_area, internal_absorption, frequencies, model	enclosure_required_transmission_loss(lp1 - nc45, 38.75, 59.5, alpha) • EnclosureResult whose panel_transmission_loss is the required R
sound_power_insulation / sound_pressure_insulation / reciprocity_insulation / artificial_source_insulation	function	What an enclosure is worth once it is built, ISO 11546-1 and -2 Eqs. (1) to (5). • sound_power_insulation(level_without, level_with, frequencies=…): D_W band by band, and D_WA from the A-weighted totals or from an explicit pair • sound_pressure_insulation(…): the same subtraction on a level at a stated position, D_p and D_pA • reciprocity_insulation(external_levels, internal_levels, …): D_pr of part 1 clause 7.2, for an enclosure that cannot be measured with its machine • artificial_source_insulation(without_by_position, with_by_position, …): the tapping plate of Annex A, averaged over source positions arithmetically, which is the standard's own word and not the energy mean used elsewhere • condition: 'laboratory' (part 1, for declaration) or 'in-situ' (part 2, for acceptance); base_standard: the row of Table 1 the levels came from	noise_control.sound_power_insulation(lw_off, lw_on, frequencies=f) • EnclosureInsulationResult
EnclosureInsulationResult	dataclass	The insertion loss of an enclosure, band by band. • frequencies [Hz], level_without, level_with, insulation [dB] • quantity: 'sound_power', 'sound_pressure' or 'reciprocity'; a_weighted_insulation [dB] • condition, source_kind, base_standard, band_fraction • .rounded(): the integers clause 9.4 reports; .plot(): the two runs, the area between them and the difference	res.rounded(), res.a_weighted_insulation
weighted_insulation / WeightedEnclosureInsulation	function / dataclass	The single-number rating of an insertion loss, 7.4 of part 1 and 7.3 of part 2. • insulation over the 16 one-third-octave rating bands or the 5 octave ones [dB], quantity, band_fraction • ISO 717-1 with D_W or D_pr written where that standard writes R, delegated to building.weighted_rating rather than re-derived • result: rating, c, ctr, unfavourable_sum, band_centres_hz, quantity	noise_control.weighted_insulation(d_w[:16]).rating
estimated_a_weighted_insulation	function	What an enclosure would be worth against a stated spectrum, Annex C of part 1 and Annex D of part 2. • spectrum_levels L_i [dB], insulation D_i [dB], frequencies [Hz] • D_WA,e = L_A − 10 lg Σ 10^(0.1 (L_i − A_i − D_i)), with A_i the printed attenuation, so A_i = −C_k against this library's band corrections • both terms are built from the same table, so the answer cannot disagree with its own inputs and an insulation of zero returns exactly zero	noise_control.estimated_a_weighted_insulation(spectrum, d_w, frequencies=f)
applicable_methods / MethodEntry	function / dataclass	Table 1 of ISO 11546 as data: which base standard may be used, and what it can give. • condition: 'laboratory' (Default) or 'in-situ'; source_kind: 'actual' (Default), 'reciprocity' or 'artificial' • each row carries base_standard, quantities, subclause and band_values: a survey-grade determination hands back an A-weighted number and nothing per band, so D_W cannot be declared from it • the reciprocity method exists in part 1 only, and asking for it in situ is refused	noise_control.applicable_methods(condition='in-situ')
test_environment_applicability / TestEnvironmentApplicability / TEST_ENVIRONMENT_REQUIREMENTS / ROOM_ABSORPTION_ESTIMATES	function / dataclass / mapping / mapping	Is this room good enough for that base standard? Annex C of ISO 11546-2. • base_standard, mean_absorption_coefficient α, room_surface_area_m2 S_V, measurement_surface_area_m2 S • S_V/S = 4/((10^(K2/10) − 1) α), which is Figure C.1 in closed form, cross-checked against emission.environmental_correction • TEST_ENVIRONMENT_REQUIREMENTS is Table C.1, the K2 ceiling and the background margin of each standard; ISO 3743-1 and ISO 3747 state no K2 at all • ROOM_ABSORPTION_ESTIMATES is Table C.2, the seven room descriptions and their α, for when nobody measured it	noise_control.test_environment_applicability(base_standard='ISO 3744', mean_absorption_coefficient=0.15, room_surface_area_m2=520.0, measurement_surface_area_m2=14.1)
leak_ratio / seal_ratio / fill_ratio / source_position_clearance_m	function	The four ratios and distances the two standards define in words. • leak_ratio(opening_area_m2, interior_surface_area_m2): θ, the openings over the interior surface; an opening with an effective silencer is not one • seal_ratio(leak): ψ = 1/θ, the same fact for a catalogue that prefers it • fill_ratio(source_volume_m3, interior_volume_m3): φ, how much of the enclosure the source fills • source_position_clearance_m(shortest_inner_dimension_m): 0,2 d, so the tapping plate is never against the panel it excites	noise_control.seal_ratio(noise_control.leak_ratio(0.02, 6.0)) # 300
UNRESTRICTED_ENCLOSURE_VOLUME_M3 / ARTIFICIAL_SOURCE_MAX_FILL_RATIO / ARTIFICIAL_SOURCE_LEAK_RATIO_ADVISORY / ARTIFICIAL_SOURCE_PLATE_MM / ARTIFICIAL_SOURCE_DROP_MM / ARTIFICIAL_SOURCE_STANDOFF_MM / ARTIFICIAL_SOURCE_EXAMPLE_LWA_DB / SOURCE_WALL_CLEARANCE_FACTOR	constant	The numbers of clause 1, clause 4 and Annex A of ISO 11546. • clause 1 applies the part without restriction to a free-standing enclosure smaller than 2 m³, and lets a larger one be measured with its actual source while the base standard's own volume limit is met; the artificial source fills at most a quarter of the interior, and clause 4 would rather keep the leak ratio under 2 % • the Annex A source is a 4 mm steel plate of 800 mm by 300 mm, dropped 40 mm onto a 60 mm standoff • the spectrum Annex B prints as an illustration totals 110 dB(A), and it was measured on a 600 mm plate rather than on the Annex A one (see the errata) • the plate stands 0,2 d from any wall	noise_control.ARTIFICIAL_SOURCE_PLATE_MM
MANDATORY_BAND_RANGE_HZ / PREFERRED_BAND_RANGE_HZ	mapping	The band range ISO 11546 and ISO 11957 require, and the one they would rather have, keyed by band fraction. • required: 100 Hz to 5 kHz in one-third octaves, 125 Hz to 4 kHz in octaves • preferred: 50 Hz to 10 kHz and 63 Hz to 8 kHz • a spectrum that does not cover the required range raises the warning of its own standard	noise_control.MANDATORY_BAND_RANGE_HZ[3] # (100.0, 5000.0)
EnclosureInsulationWarning / CabinInsulationWarning	warning class	The measurement is outside a condition ISO 11546 or ISO 11957 states. • a band range short of the required one, a base standard that gives only an A-weighted value, a margin under 6 dB over the background • a room-to-cabin volume ratio under 20, a lowest band outside the range clause 6.2 covers	warnings.simplefilter('error', CabinInsulationWarning) Emitted by noise_control.enclosure_insulation
cabin_insulation / CabinInsulationResult	function / dataclass	What a cabin keeps out, ISO 11957 Eqs. (1), (2) and (3). • room_levels, cabin_levels [dB], frequencies [Hz], band_fraction • method: 'laboratory' (Default), 'in-situ-loudspeaker' or 'in-situ-actual-noise'; the in-situ pair carries the prime of definition 3.6 • room_background_levels / cabin_background_levels: taken off by the ISO 3741 correction 6.4 asks for • a_weighted_room_level / a_weighted_cabin_level: Eq. (3), defined for the actual-noise method alone, and refused under any other • result: insulation, apparent, symbol, a_weighted_insulation, internal_noise_level, .rounded(), .plot()	noise_control.cabin_insulation(room, cabin, frequencies=f)
weighted_cabin_insulation / WeightedCabinInsulation	function / dataclass	The single-number rating of a cabin, ISO 11957 clause 8. • insulation over the rating bands [dB], apparent, band_fraction • ISO 717-1 with D_p or D'_p written where that standard writes R • clause 4 calls this the preferred single number and then warns against reading too much into it, because what a cabin is worth depends on the spectrum it stands in	noise_control.weighted_cabin_insulation(d_p[:16]).rating
estimated_cabin_noise_insulation / internal_noise_level	function	Annex A and 6.7 of ISO 11957: the cabin against a stated spectrum, and the noise it makes on its own. • estimated_cabin_noise_insulation(spectrum_levels, insulation, frequencies=…): D_pA,e = L_A − 10 lg Σ 10^(0.1 (L_i − A_i − D_pi)), the same identity and the same A_i sign as the enclosure annexes • internal_noise_level(levels, background_level=…): L_pA, the energy mean over the 0,3 m sphere with the external sources off • the background rule of 6.7 is not the one of 6.4: the correction is made only while the margin stays between 6 dB and 10 dB, and below 6 dB the answer is an upper bound	noise_control.internal_noise_level([58.2, 59.1, 58.7], background_level=51.0)
check_source_positions / SourcePositionCheck / MIN_SOURCE_POSITIONS_IN_SITU / MAX_SOURCE_POSITIONS_IN_SITU	function / dataclass / constant	Were there enough loudspeaker positions? ISO 11957 7.2.1. • insulation_by_position: D'_p in octave bands, one row per source position • the number of positions shall be at least the largest difference in decibels between any two of them, three to begin with and six at most • result: positions_used, max_octave_spread_db, required_positions, satisfied, exceeds_maximum, the last of which 7.2.1 says shall be stated in the report • the clause says octave bands, so one-third-octave data is folded at the level and not at the difference	noise_control.check_source_positions(d_p_by_position).satisfied
check_band_flatness / BandFlatnessCheck / BAND_FLATNESS_LIMIT_DB / DEFAULT_BAND_FLATNESS_LIMIT_DB	function / dataclass / mapping / constant	Is the driving spectrum flat enough inside each octave? ISO 11957 6.4 and 7.2.1. • third_octave_levels [dB], frequencies [Hz], read three bands to an octave • 6 dB in the octave of 125 Hz, 5 dB in the one of 250 Hz, 4 dB above; nothing is printed below 125 Hz, so limit_db is nan there and the octave counts as satisfied • result: octave_centres_hz, spread_db, limit_db, satisfied, .all_satisfied	noise_control.check_band_flatness(lp, frequencies=f).all_satisfied
minimum_cabin_clearance_m / WALL_CLEARANCE_FACTOR / LOW_BAND_CLEARANCE_M / LOW_BAND_CLEARANCE_RANGE_HZ	function / constant	How far the cabin stands from the room, ISO 11957 6.2. • lowest_band_frequency_hz, speed_of_sound [m/s] (Default: 343) • half a wavelength at the lowest band of interest, from the walls, the ceiling and any diffusing element alike • from 50 Hz to 80 Hz the clause fixes a flat 2 m instead, which at 50 Hz is less than the half wavelength above it would have asked for: the low-frequency sentence relaxes the rule rather than tightening it, and it is written as printed (see the errata)	noise_control.minimum_cabin_clearance_m(100.0) # 1.715 m
uncertainty_conditions / CabinUncertainty / MIN_ROOM_TO_CABIN_VOLUME_RATIO / STATED_UNCERTAINTY_BAND_RANGE_HZ / INCREASED_UNCERTAINTY_BAND_RANGE_HZ / IN_SITU_EXCESS_STANDARD_DEVIATION_DB	function / dataclass / constant	What ISO 11957 clause 10 is willing to say about a measurement. • room_volume_m3, cabin_volume_m3, method • in the laboratory the uncertainty of ISO 3741 carries over from 250 Hz to 10 kHz, while the room is at least 20 times the volume of the cabin; from 50 Hz to 200 Hz, and below that ratio, a larger uncertainty is expected • the loudspeaker method in situ adds about 2 dB to the standard deviation • for the actual-noise method the clause states nothing and sends a declared value to ISO 4871, so stateable is False	noise_control.uncertainty_conditions(room_volume_m3=300.0, cabin_volume_m3=12.0)
MIN_LOUDSPEAKER_SEPARATION_M / MIN_SOURCE_TO_CABIN_M / MIN_SOURCE_TO_MICROPHONE_M / MIN_SOURCE_TO_MICROPHONE_IN_SITU_M / MAX_MICROPHONE_TO_CABIN_M / MIN_MICROPHONE_HEIGHT_M / OPERATOR_SPHERE_RADIUS_M / OPERATOR_PATH_INCLINATION_DEG / INTERNAL_NOISE_CENTRE_HEIGHT_M / INTERNAL_NOISE_CENTRE_TOLERANCE_M / MIN_FIXED_MICROPHONE_POSITIONS / MIN_LOUDSPEAKER_POSITIONS	constant	The geometry of ISO 11957 6.4, 6.5 and 7.4, as numbers rather than as prose. • loudspeakers at least 3 m apart and 2 m from the cabin; 2 m from a microphone in the laboratory and 3 m in situ, which is a deliberate difference • in a large room with a short reverberation time, no microphone further than 5 m from the outside of the cabin • inside, no position closer than 0,2 d to a surface and none below 1 m; with a defined operator position, three points on a sphere of radius 0,3 m, or a path inclined 45° • for the internal noise level the centre of that sphere is 1,55 m ± 0,075 m above the floor • at least six fixed microphone positions and two loudspeaker positions in the laboratory; 7.4 fixes the microphones at exactly six	noise_control.OPERATOR_SPHERE_RADIUS_M # 0.3
MAX_LEAK_RATIO / MIN_SIGNAL_TO_BACKGROUND_DB / PREFERRED_SIGNAL_TO_BACKGROUND_DB / INTERNAL_NOISE_CORRECTION_WINDOW_DB	constant	The four thresholds ISO 11957 states as conditions rather than as advice. • clause 1 applies the standard to a cabin of leak ratio 2 % or less, where ISO 11546 only prefers the same figure • 6 dB over the background, and preferably more than 12 dB, in every band of interest • 6.7 corrects the internal noise level only while the margin is between 6 dB and 10 dB	noise_control.MAX_LEAK_RATIO # 0.02
in_situ_transmission_loss / in_situ_insertion_loss / SilencerInSituResult	function / function / dataclass	What a silencer is worth where it stands, ISO 11820 Eqs. (19) and (21). • in_situ_transmission_loss(source_levels_db, receiver_levels_db, source_area_m2=, receiver_area_m2=): D_ts = D_tps + 10 lg(S₂/S₁) + K₂ − K₁ • in_situ_insertion_loss(levels_without_db, levels_with_db, area_without_m2=, area_with_m2=): the same form with the two runs of Eq. (3) in place of the two sides • each area and field_correction_difference_db [dB] take one value or one per band: the area of a diffuse room is a quarter of its absorption and moves with T, so pass what reverberant_surface_area_m2 returns • case: which installation of Figure 1 the numbers came from, checked against the quantity • result: loss_db, level_difference_db, area_term_db and field_correction_difference_db (always per band), quantity, .plot()	noise_control.in_situ_transmission_loss(l2, l1, source_area_m2=0.9, receiver_area_m2=18.0)
installation_case / InstallationCase / INSTALLATION_CASES	function / dataclass / mapping	The twenty installations of Figure 1 as data, with the area rules clause 9 gives each. • number 1 to 20, source_side / receiver_side: 'duct', 'room' or 'outdoors' • quantity: 'transmission' for 1 to 16, 'insertion' for 17 to 20 • source_area_rule / receiver_area_rule: the duct cross-section, a quarter of the room absorption, a hemisphere or the aperture in the wall	noise_control.installation_case(7).receiver_area_rule
transmission_level_difference_db / insertion_level_difference_db / mean_sound_pressure_level_db	function	The level differences ISO 11820 builds everything else from, Eqs. (1), (3) and (2). • transmission_level_difference_db(source_levels_db, receiver_levels_db): across the silencer • insertion_level_difference_db(levels_without_db, levels_with_db): between the run without it and the run with it • mean_sound_pressure_level_db(levels_db): the energy mean over the measuring points	noise_control.mean_sound_pressure_level_db([71.2, 73.4, 72.0])
sound_power_level_db / reverberant_surface_area_m2 / SABINE_AREA_COEFFICIENT	function / function / constant	From a mean level to a sound power, Eqs. (5), (7), (9) and (11), and the area a reverberant room stands in for, Eqs. (6), (10) and (12). • L_W = L̄_p + 10 lg(S/S₀) + K, with S₀ = 1 m² and S whichever area the case calls for • reverberant_surface_area_m2(volume_m3, reverberation_time_s, speed_of_sound=340.0): S = 6 ln10 V / (c T), a quarter of the Sabine absorption area • SABINE_AREA_COEFFICIENT is that 6 ln10, the 13,8 the three equations share	noise_control.reverberant_surface_area_m2(320.0, t20)
extraneous_corrected_mean_level_db / silencer_background_correction_db / ISO11820_BACKGROUND_CORRECTIONS_DB / MAXIMUM_EXTRANEOUS_CORRECTION_DB / ISO11820_MINIMUM_BACKGROUND_MARGIN_DB / ISO11820_NEGLIGIBLE_BACKGROUND_MARGIN_DB	function / function / mapping / constant	The two routes ISO 11820 offers around extraneous sound, 9.1.1 to 9.1.3. • extraneous_corrected_mean_level_db(levels_db, extraneous_levels_db): the energy subtraction of Eqs. (17) and (18), and whether it hit the 3 dB cap past which the quantity is not determined, judged on the margin of the two energy means as Table 1 draws it: a 3 dB margin, a 3,02 dB correction, is still determined • silencer_background_correction_db(level_difference_db): Table 1, in decibels to take off, stepped from 3 dB at a margin of 3 dB to 0,5 dB at 9 or 10 • a margin under 3 dB is refused; above 10 dB nothing is corrected, and 10 dB itself still takes off 0,5 dB	noise_control.silencer_background_correction_db([4.0, 9.0]) # 2.0, 0.5
temperature_field_correction_db / TYPICAL_FIELD_CORRECTION_LIMIT_DB / ISO11820_SOUND_SPEED_M_S	function / constant	What a difference of temperature does to the field correction, Eqs. (20) and (22). • K₂ − K₁ = 5 lg[(273 + θ₁)/(273 + θ₂)], the standard's own 273 rather than 273,15 • the same expression serves the insertion measurement, with the with-silencer run as the receiver side • NOTE 4 expects K to stay under 3 dB in absolute value once the areas are the ones 3.3 and 3.4 define	noise_control.temperature_field_correction_db(receiver_temperature_c=20.0, source_temperature_c=120.0)
octave_levels_from_third_octave_db / ISO11820_OCTAVE_BAND_RANGE_HZ / ISO11820_OCTAVE_BAND_EXTENDED_RANGE_HZ / ISO11820_THIRD_OCTAVE_BAND_RANGE_HZ / ISO11820_THIRD_OCTAVE_BAND_EXTENDED_RANGE_HZ	function / constant	The bands ISO 11820 measures in, 9.1.5 and 8.1. • octave_levels_from_third_octave_db(levels_db): threes folded into octaves, the route the clause allows when the narrower bands were measured • 63 Hz to 4 kHz in octaves, 50 Hz to 5 kHz in one-third octaves, with the extended ranges the clause names for a silencer that works outside them	noise_control.octave_levels_from_third_octave_db(third_octave_levels)
total_pressure_loss_pa / static_pressure_difference_pa / velocity_pressure_pa / flow_velocity_m_s / gas_density_kg_m3 / silencer_flow_velocity_m_s / ISO11820_GAS_CONSTANT / ISO11820_AIR_GAS_CONSTANT / ISO11820_AMBIENT_PRESSURE_PA / VELOCITY_UNIFORMITY_TOLERANCE_PERCENT	function / constant	The flow side of the measurement, Eqs. (13) to (16) and (27) to (31). • pressure loss Δp_T, the static difference Δp_S behind a change of area, the velocity pressure and the velocity it stands for • gas_density_kg_m3(temperature_c=, molar_mass_kg_kmol=None): ρ = M p_amb / [R (273 + θ)], with R/M = 287 N m per kg K for air • silencer_flow_velocity_m_s: the upstream mean velocity scaled by S_u/S_f, which is the velocity the regenerated noise answers to • 9.2 asks the velocity profile to be uniform within 10 %	noise_control.gas_density_kg_m3(temperature_c=120.0)
measurement_distance_upstream_m / measurement_distance_downstream_m / UPSTREAM_DISTANCE_DIAMETERS / DOWNSTREAM_DISTANCE_COEFFICIENTS	function / constant	Where the measurement surfaces stand along the duct, Eqs. (15) and (16). • upstream: one and a half equivalent diameters of the measurement cross-section • downstream: 12 √S_d − 10 √S_f, which can fall to zero for a silencer whose free area is most of the duct, and 8.3.1 then sends the parties to agree • S_f is the free cross-section, which NOTE 18 warns is not the intake one	noise_control.measurement_distance_downstream_m(0.9, 0.45)
SilencerInSituWarning	warning class	The measurement is outside a condition ISO 11820 states. • a downstream distance the geometry cannot give, a field correction past what NOTE 4 expects, a velocity profile outside the 10 % the standard asks for	warnings.catch_warnings() Emitted by noise_control.silencer_in_situ
screen_attenuation / ScreenInSituResult	function / dataclass	What a removable screen is worth where it stands, ISO 11821 clauses 5.8 and 5.9. • unscreened_levels_db, screened_levels_db [dB], frequencies [Hz], distance_m • source_kind: 'actual' (Default) or 'artificial' • a_weighted_unscreened_level_db / a_weighted_screened_level_db: the pair of 5.9, refused with an artificial source because the spectrum would be the loudspeaker's • result: attenuation_db, a_weighted_attenuation_db, .plot() • .rounded() and .rounded_a_weighted(): the whole decibels 7.4 c) reports, an exact half to the even one	noise_control.screen_attenuation(without, with_screen, frequencies=f)
background_corrected_level_db / BACKGROUND_CORRECTION_WINDOW_DB / ISO11821_MINIMUM_BACKGROUND_MARGIN_DB / ISO11821_PREFERRED_BACKGROUND_MARGIN_DB	function / constant	The background correction ISO 11821 boxes, clause 5.7. • L_p = 10 lg(10^(L_ps/10) − 10^(L_pb/10)), the plain energy subtraction, band by band and position by position • over 10 dB of margin nothing is corrected; under 6 dB the conditions are "not acceptable", which is a refusal, because the background it names includes wind noise • where ISO 11820 corrects from a stepped table, this standard prints the formula	noise_control.background_corrected_level_db(levels, background)
directivity_index_db / DIRECTIVITY_POSITIONS / DIRECTIVITY_INDEX_LIMIT_DB / DIRECTIVITY_CIRCLE_RADIUS_M	function / constant	Is this loudspeaker omnidirectional enough? ISO 11821 definition 3.10 and 5.2.2. • twelve positions evenly spaced on a horizontal circle of about 1,5 m radius • DI_i = L₃₆₀ − L₃₀,i, the logarithmic mean less the position, so the index is positive where the position is quieter than the mean • the source qualifies while no position falls more than 8 dB below the mean	noise_control.directivity_index_db(levels_at_twelve)
microphone_distances_m / SCREEN_DISTANCE_FACTORS / MINIMUM_MICROPHONE_DISTANCE_M / MINIMUM_SCREEN_DIMENSION_M	function / constant	Where the microphones stand in front of a screen, ISO 11821 5.5.2. • a quarter, a half, once and twice the screen height, never closer than 1 m, so for a low screen the two nearest positions coincide • NOTE 2 reads the spread: the smallest attenuation at the most remote position, the largest at the nearest • a screen under 1,5 m in either dimension is outside the standard, and that is reported	noise_control.microphone_distances_m(3.0)
impulse_mean_level_db / IMPULSE_REPEATS / IMPULSE_REPEAT_DEVIATION_DB / IMPULSE_INVALID_DEVIATION_DB	function / constant	A single-impulse source, ISO 11821 5.6.2.1. • at least three repeats with the S time weighting, and the arithmetic mean of them, which is what the clause asks for • a spread past 3 dB asks for three more repeats, which is reported • a spread past 5 dB makes the measurement invalid, which is refused	noise_control.impulse_mean_level_db([88.1, 89.4, 87.9])
ISO11821_BAND_RANGE_HZ / OPERATOR_HEIGHT_M / OPERATOR_HEIGHT_TOLERANCE_M / OUTDOOR_RANGE_M / ENGINEERING_STANDARD_DEVIATION_DB	mapping / constant	The conditions ISO 11821 states as numbers. • 100 Hz to 5 kHz in one-third octaves, 125 Hz to 4 kHz in octaves • a microphone stands at 1,55 m ± 0,075 m where no operator height is given, in the sphere of 0,3 m radius the cabin standard also prints • outdoors the method reaches 25 m from the screen, and its standard deviation of reproducibility is 2 dB, which is engineering grade	noise_control.ISO11821_BAND_RANGE_HZ[3] # (100.0, 5000.0)
ScreenInSituWarning	warning class	The measurement is outside a condition ISO 11821 states. • a screen smaller than 1,5 m, a spread of repeats past 3 dB, a distance past the 25 m the outdoor method reaches	warnings.catch_warnings() Emitted by noise_control.screen_in_situ
valve_aerodynamic_noise	function	Control valve aerodynamic noise, the whole of IEC 60534-8-3 Clause 5. • stream: a GasStream, valve: a ValveTrim, pipe: a DownstreamPipe • the three groups are the standard's own reading order: the operating point, the valve at that travel, and the pipe the noise comes out of	res = noise_control.valve_aerodynamic_noise(stream, valve, pipe) • AerodynamicValveNoise
AerodynamicValveNoise	dataclass	What Clause 5 says about one operating point. • regime (1 to 5), boundaries, pressure_ratio x, vena_contracta_pressure_pa [Pa] • jet_diameter_m [m], mach, acoustical_efficiency, stream_power / sound_power [W], sound_power_level [dB] • peak_frequency [Hz], outlet_mach, pipe_mach, velocity_correction [dB], internal_level [dB] • frequencies and the three band arrays, plus external_level, the A-weighted single number of Eq. (25) [dB(A)] at 1 m	res.regime, res.external_level
GasStream / ValveTrim / DownstreamPipe	dataclass	The three groups of input IEC 60534-8-3 reads. • GasStream: mass_flow [kg/s], inlet_pressure_pa / outlet_pressure_pa [Pa], inlet_density [kg/m3], inlet_temperature_k [K], specific_heat_ratio, molecular_mass [kg/kmol] • ValveTrim: flow_coefficient C, style_modifier F_d, pressure_recovery F_L or F_LP/F_p, outlet_diameter_m D [m], efficiency_correction A_eta and strouhal_number St_p from Table 4, coefficient 'Cv' (Default) or 'Kv' • DownstreamPipe: internal_diameter_m D_i [m], wall_thickness t_S [m], density [kg/m3], and the printed defaults speed_of_sound, air_sound_speed, atmospheric_pressure_pa, standard_pressure_pa	noise_control.ValveTrim(flow_coefficient=90.0, ...)
pressure_ratio_boundaries / RegimeBoundaries	function / dataclass	The four pressure ratios of Eqs. (3) to (7) that cut Clause 5.2 into five regimes. • specific_heat_ratio, pressure_recovery • vena_contracta x_vcc, critical x_C, break_point x_B, constant_efficiency x_CE, recovery alpha	noise_control.pressure_ratio_boundaries(1.22, 0.8)
flow_regime	function	Which of the five regimes a pressure ratio falls in (Clause 5.2). • pressure_ratio x, boundaries • Each interval closed at the top; regime V starts strictly above x_CE, as the clause prints it and not as Table 3 does	noise_control.flow_regime(0.52, bounds) # 3
valve_style_modifier	function	F_d of Eqs. (8a) to (8c): the hydraulic diameter of one passage over the diameter of the equivalent single orifice. • passage_area A [m2], wetted_perimeter l_w [m], passages N_o	noise_control.valve_style_modifier(0.00137, 0.181, 6) # 0.30
jet_diameter_m	function	D_j of Eq. (9), the length scale the peak frequency is set by. • flow_coefficient C, style_modifier F_d, pressure_recovery • coefficient: 'Cv' (Default) or 'Kv'	noise_control.jet_diameter_m(90.0, 0.30, 0.805) # m
internal_spectrum	function	Eq. (19): the internal level spread over the third-octave bands around the peak. • internal_level [dB], peak_frequency [Hz], frequencies [Hz] • Falls as f^-2.5 above the peak and f^1.7 below it	noise_control.internal_spectrum(155.3, 7778.0, bands)
pipe_transmission_loss	function	Eq. (20a): what the pipe wall keeps in, band by band (negative). • frequencies [Hz] • internal_diameter_m, wall_thickness, valve_outlet_diameter_m [m] • downstream_density [kg/m3], downstream_sound_speed [m/s], pipe_density [kg/m3] • pipe_sound_speed, air_sound_speed, atmospheric_pressure_pa, standard_pressure_pa	noise_control.pipe_transmission_loss(bands, internal_diameter_m=0.2, ...)
coincidence_frequencies / PipeFrequencies	function / dataclass	The ring and two coincidence frequencies of Eqs. (21) to (23) that shape the transmission loss. • internal_diameter_m, wall_thickness, downstream_sound_speed • ring f_r, internal_coincidence f_o, external_coincidence f_g	noise_control.coincidence_frequencies(0.2, 0.008, 408.0)
multistage_trim_conditions / MultistageConditions	function / dataclass	Clause 6.3: what a multistage trim hands Clause 5 in place of the valve inlet (Eqs. (27) to (29)). • inlet_pressure_pa, outlet_pressure_pa [Pa], inlet_density [kg/m3] • flow_coefficient C of the valve, last_stage_coefficient C_n • result: flow_coefficient, stagnation_pressure_pa p_n, stagnation_density rho_n, and equation: which of '28a', '28b', '28c' NOTE 3 selected	noise_control.multistage_trim_conditions(inlet_pressure_pa=7e6, ...)
last_stage_flow_coefficient / LAST_STAGE_AREA_CONSTANTS	function / constant	Eq. (27): C_n = N_16 A_n, the flow coefficient of the last stage from its total flow area. • total_area A_n [m2] • coefficient: 'Cv' (Default) or 'Kv', selecting N_16 from Table 1 6.3 asks for this only when the manufacturer states no C_n	noise_control.last_stage_flow_coefficient(6.44e-3) → 315
multiple_passage_jet_diameter / MAXIMUM_PASSAGE_ASPECT	function / constant	Eq. (26): the jet diameter of a single-stage, many-passage trim, where [0.9 - 0.06 l/d] replaces the pressure recovery factor. • flow_coefficient, style_modifier, passage_length l [m], passage_diameter_m d [m] • coefficient: 'Cv' (Default) or 'Kv' • l/d capped at 4 by NOTE 1, since the bracket would reach zero at 15	noise_control.multiple_passage_jet_diameter(90.0, 0.094, 0.02, 0.01)
stage_level_correction	function	Eq. (31): what the stages before the last one add back. • last_stage_level L_pi,n [dB], stages n (≥ 2), inlet_pressure_pa p_1, stagnation_pressure_pa p_n [Pa] L_pi = L_pi,n + 10 lg(p_1/p_n)/(n-1)^0.125, so the stage count barely moves it	noise_control.stage_level_correction(150.0, 3, 7e6, 2.1e6)
expander_noise / ExpanderNoise	function / dataclass	Clause 7: what the flow leaving the valve outlet makes (Eqs. (34) to (42)). • frequencies [Hz] • mass_flow, downstream_density, downstream_sound_speed • internal_diameter_m D_i, throat_diameter_m d_i (the smaller of valve outlet and expander inlet) [m] • velocity_correction L_g [dB], expander • result: pipe_velocity (capped at Mach 0.8), inlet_velocity (capped at c_2), mach, stream_power, acoustical_efficiency, sound_power, peak_frequency, internal_level, band_internal_level	noise_control.expander_noise(bands, mass_flow=0.89, ...)
Expander / DEFAULT_EXPANDER	dataclass / constant	The transition piece downstream of the valve, limited by 7.1 to 30 degrees of total included angle. • contraction beta (Default: 0.93, the NOTE 1 figure for straight pattern globe valves; some rotary valves reach 0.7) • efficiency_correction A_eta (Default: -3.0, Table 4's own expander row) • strouhal_number St_p (Default: 0.2)	noise_control.Expander(contraction=0.7)
combine_internal_levels	function	Eq. (43): two spectra at the same pipe wall, added in energy. • *levels: two or more band level arrays of one shape [dB] The valve trim and the outlet flow are two sources inside one pipe, and only the sum crosses the wall	noise_control.combine_internal_levels(trim, outlet)
ValveNoiseWarning	warning class	A valve read outside the conditions IEC 60534-8-3 prints for it. • emitted when the valve outlet passes the Mach 0.3 of NOTE 1 to Eq. (15) and no expander was given, so the second source is missing from the answer	warnings.simplefilter('error', noise_control.ValveNoiseWarning)
EXPANDER_PIPE_MACH_LIMIT / GLOBE_CONTRACTION_COEFFICIENT	constant	0.8, the Mach number Eq. (34) caps the downstream pipe velocity at, and 0.93, the contraction coefficient NOTE 1 to Eq. (35) gives for straight pattern globe valves.	noise_control.EXPANDER_PIPE_MACH_LIMIT
VALVE_ACOUSTIC_STYLES	constant	Table 4: (A_eta, St_p) for the thirteen valve styles the table prints, from the globe parabolic plug to the expander.	noise_control.VALVE_ACOUSTIC_STYLES['globe ported cage'] → (-3.8, 0.2)
FLOW_COEFFICIENT_CONSTANTS	constant	Table 1: N_14 for the two flow coefficients, {'Cv': 4.6e-3, 'Kv': 4.9e-3}. Both are rounded to two digits, so the same valve rated either way differs by 1 %.	noise_control.FLOW_COEFFICIENT_CONSTANTS
AERODYNAMIC_A_WEIGHTING_DB	constant	Table 7: the A weighting the standard prints for its own 33 bands, which Eq. (25) sums with.	noise_control.AERODYNAMIC_A_WEIGHTING_DB[19] → 0.0
MACH_LIMIT_STANDARD_TRIM / PIPE_WALL_MACH_LIMIT	constant	0.3 in both cases: the valve outlet Mach number above which Clause 5 gives way to Clause 7 (NOTE 1 to Eq. (15)), and the ceiling NOTE 2 puts on the pipe Mach number before Eq. (16).	noise_control.MACH_LIMIT_STANDARD_TRIM
AIR_SOUND_SPEED_M_S / PIPE_SOUND_SPEED_M_S	constant	343 m/s and 5000 m/s, the values NOTES 3 and 4 print for the coincidence frequencies; the second is why Clause 1 restricts the method to steel pipe.	noise_control.PIPE_SOUND_SPEED_M_S
STANDARD_ATMOSPHERE_PA	constant	101325 Pa, the atmosphere Eqs. (20a) and (20c) are printed for. It is p_a and p_s both, which the standard keeps apart because a pipe can run at one and be rated at the other.	noise_control.STANDARD_ATMOSPHERE_PA
STRUCTURAL_LOSS_REFERENCE_HZ / UNIVERSAL_GAS_CONSTANT	constant	1.0 Hz, the f_s of Eq. (20c) that the equation never names again, and 8314 J/(kmol K), paired with a molecular mass in kg/kmol as Eqs. (10) and (14) are written for.	noise_control.UNIVERSAL_GAS_CONSTANT
REGIME_SUBSONIC / REGIME_CHOKED / REGIME_SUPERSONIC / REGIME_SHOCK / REGIME_CONSTANT_EFFICIENCY / REGIME_COUNT	constant	1 to 5, the five regimes of Clause 5.2 by the number it prints, and their count.	res.regime == noise_control.REGIME_SHOCK
valve_hydrodynamic_noise	function	Control valve hydrodynamic noise, the whole of IEC 60534-8-4 Clauses 4 and 5. • stream: a LiquidStream, valve: a LiquidTrim, pipe: a LiquidPipe • strouhal_form: 'annex' (Default) or 'clause', the two printings of Eq. (12) • frequency (Default: the 50 Hz to 20 kHz thirds of 5.4.1)	res = noise_control.valve_hydrodynamic_noise(stream, valve, pipe) • HydrodynamicValveNoise
LiquidStream / LiquidTrim / LiquidPipe	dataclass	The three groups of input IEC 60534-8-4 reads. • LiquidStream: mass_flow [kg/s], inlet_pressure_pa / outlet_pressure_pa / vapour_pressure_pa [Pa], density [kg/m3], speed_of_sound [m/s] • LiquidTrim: flow_coefficient C, style_modifier F_d, pressure_recovery F_L, incipient_ratio x_Fz, power_ratio r_W (Table 2), valve_diameter_m d and seat_diameter_m d_o [m], coefficient 'Cv' (Default) or 'Kv' • LiquidPipe: internal_diameter_m D_i [m], wall_thickness t_p [m], density [kg/m3], and the printed defaults speed_of_sound, air_density, air_sound_speed	noise_control.LiquidTrim(flow_coefficient=90.0, ...)
HydrodynamicValveNoise	dataclass	What IEC 60534-8-4 says about one operating point on a liquid line. • regime ('turbulent' / 'cavitating'), pressure_ratio x_F, differential and cavitation_differential [Pa], incipient_ratio / corrected_ratio • jet_diameter_m [m], velocity U_vc [m/s], stream_power / sound_power [W], turbulent_efficiency / cavitation_efficiency • internal_level [dB], strouhal_number, turbulent_peak / cavitation_peak [Hz] • pipe_ring_frequency [Hz], reference_transmission_loss, turbulent_transmission_loss, cavitation_transmission_loss, transmission_loss [dB] • frequencies and the three band arrays, plus external_level at 1 m, which the standard labels A-weighted although neither Eq. (18a) nor (18b) applies a weighting	res.regime, res.external_level
differential_pressure_ratio / cavitation_differential	function	Eqs. (1) and (2): how far towards flashing the operating point is, and the differential the jet velocity is computed from. • keyword-only: inlet_pressure_pa, outlet_pressure_pa, vapour_pressure_pa [Pa]; the second also takes pressure_recovery • x_F = (p1 - p2)/(p1 - p_v); Delta p_c is the lesser of p1 - p2 and F_L^2 (p1 - p_v)	noise_control.differential_pressure_ratio(inlet_pressure_pa=1e6, outlet_pressure_pa=8e5, vapour_pressure_pa=2320.0) # 0.2005
incipient_cavitation_ratio / multihole_incipient_cavitation_ratio / corrected_incipient_ratio	function	Eqs. (3a), (3b) and (3c): where cavitation becomes audible. • (3a): flow_coefficient, style_modifier, pressure_recovery, coefficient 'Cv' (Default) / 'Kv' • (3b): passages N_o, hole_diameter_m d_H [m], pressure_recovery • (3c) moves x_Fz from the 6e5 Pa the charts are drawn at to the working inlet_pressure_pa 4.2 asks for a value measured to IEC 60534-8-2; these are the estimates it offers instead	noise_control.incipient_cavitation_ratio(90.0, 0.42, 0.92) # 0.2543
vena_contracta_velocity / mechanical_stream_power	function	Eqs. (5) and (6): the jet velocity and the stream power it carries. • differential Delta p_c [Pa], density [kg/m3], pressure_recovery • mass_flow [kg/s], velocity [m/s], pressure_recovery	noise_control.vena_contracta_velocity(2e5, 997.0, 0.92) # 21.77 m/s
turbulent_efficiency / cavitation_efficiency	function	Eqs. (8) and (9): the two acoustical efficiencies the sound power is a fraction of. • turbulent: velocity, speed_of_sound; 1e-4 at U_vc = c_L and linear below it • cavitating (keyword-only): turbulent, differential, choked_differential, pressure_ratio, corrected_ratio Exactly zero on the threshold, so the two regimes meet without a step	noise_control.turbulent_efficiency(21.77, 1400.0) # 1.555e-6
internal_sound_pressure_level	function	Eq. (10): the level inside, at the pipe wall. • keyword-only: sound_power W_a [W], density and speed_of_sound of the liquid, internal_diameter_m D_i [m] The liquid's impedance is in the numerator, which is why a water line runs 150 dB inside	noise_control.internal_sound_pressure_level(sound_power=0.00234, density=997.0, speed_of_sound=1400.0, internal_diameter_m=0.1071)
jet_strouhal_number / turbulent_peak_frequency / cavitation_peak_frequency	function	Eqs. (12), (11) and (13): where the noise sits in frequency. • jet_strouhal_number (keyword-only): flow_coefficient, style_modifier, pressure_recovery, corrected_ratio, valve_diameter_m, seat_diameter_m, inlet_pressure_pa, vapour_pressure_pa, coefficient, form 'annex' (Default) / 'clause' • turbulent_peak_frequency(strouhal_number, velocity, jet) • cavitation_peak_frequency(turbulent_peak, pressure_ratio, corrected_ratio): six times the turbulent peak on the threshold, falling from there	noise_control.cavitation_peak_frequency(654.35, 0.3508, 0.2386)
pipe_ring_frequency / reference_transmission_loss / transmission_loss_correction	function	Eqs. (14), (15), (16b) and (22b): the pipe wall. • pipe_ring_frequency(internal_diameter_m, pipe_sound_speed=5000) • reference_transmission_loss(internal_diameter_m, wall_thickness, pipe_density=…, air_density=…, …), negative by construction and therefore added downstream • transmission_loss_correction(frequency, ring): one expression for both printed equations, scalar or per band	noise_control.reference_transmission_loss(0.1071, 0.0036, pipe_density=7800.0) # -44.7 dB
cavitation_transmission_loss	function	Eq. (17): what cavitation does to the wall. • turbulent_loss [dB]; keyword-only turbulent_peak, cavitation_peak [Hz], efficiency_ratio • pressure_ratio and corrected_ratio apply the NOTE's floor, which keeps the cavitating loss from falling below the turbulent one within 0.1 of the threshold	noise_control.cavitation_transmission_loss(-71.84, turbulent_peak=654.35, cavitation_peak=1088.94, efficiency_ratio=0.377)
turbulent_distribution / cavitation_distribution / band_internal_levels	function	Eqs. (20a), (20b), (19a) and (19b): the internal level, band by band. • the two distributions take frequency and their own peak, and return a dB correction • band_internal_levels(frequency, internal_level, *, turbulent_peak, cavitation_peak=None, cavitation_fraction=0.0) weights the two by their share of the sound power Turbulent: 3 dB per octave up, 9 dB down. Cavitating: 4.5 dB both ways	noise_control.band_internal_levels(bands, 156.5, turbulent_peak=654.4, cavitation_peak=1088.9, cavitation_fraction=0.377)
stage_conditions / StageConditions / combine_stage_levels	function / dataclass / function	Clause 6: Eqs. (23a) to (24b), (26) and (27) for a multistage trim. • stage_conditions (keyword-only): inlet_pressure_pa, outlet_pressure_pa, vapour_pressure_pa, stage_coefficients C_i, flow_coefficient C • each stage takes a share of the differential in inverse proportion to its own C_i squared, the series law 1/C^2 = sum(1/C_i^2) • StageConditions: inlet_pressure_pa, outlet_pressure_pa, pressure_ratio • combine_stage_levels(*levels): the energy sum of Eq. (27)	noise_control.stage_conditions(inlet_pressure_pa=1e6, outlet_pressure_pa=4e5, vapour_pressure_pa=2320.0, stage_coefficients=[156.0]*3, flow_coefficient=90.0)
last_stage_differential / uniform_passage_style_modifier / last_stage_seat_diameter_mm	function	6.3.2: the fixed multistage device, where only the last stage is calculated. • last_stage_differential (keyword-only, Eq. (28)) caps the differential at the cavitation threshold of the last stage, not at F_L^2 as Eq. (2) does • uniform_passage_style_modifier(passages) = 1/sqrt(N_o), Eq. (29) • last_stage_seat_diameter_mm(flow_coefficient, coefficient='Cv'): the unnumbered 5.2 sqrt(N_34 C_n), which returns millimetres for a symbol Clause 3 declares in metres (see docs/ERRATA.md)	noise_control.uniform_passage_style_modifier(16) # 0.25
ACOUSTIC_POWER_RATIOS / CAPACITY_SCALE_CONSTANTS	constant	Table 2: r_W for the twelve valves and fittings the table prints, a quarter for the globes and rotaries, a half for the butterflies, one for an expander. Table 1: N_34, {'Cv': 1.17, 'Kv': 1.0}	noise_control.ACOUSTIC_POWER_RATIOS['globe parabolic plug'] # 0.25
STROUHAL_CONSTANTS / REFERENCE_INLET_PRESSURE_PA / CAVITATION_FLOOR_WIDTH / AIR_DENSITY_KG_M3	constant	The two printings of Eq. (12), {'annex': 0.036, 'clause': 0.02}; 6e5 Pa, the inlet pressure x_Fz is drawn at; 0.1, the width in x_F of the band the NOTE to Eq. (17) floors the efficiency ratio in; 1.293 kg/m3 for the air outside the pipe	noise_control.STROUHAL_CONSTANTS['annex']
EnclosureResult	dataclass	Enclosure insertion-loss result. • panel_transmission_loss, correction C, insertion_loss, room_constant, external_area, internal_area • .plot()	res.insertion_loss
program_loudness	function	EBU R 128 measurement set of a programme (BS.1770-5 + Tech 3341/3342). • x: signal (1D mono or 2D [channels, samples], 1.0 = 0 dBFS) • fs [Hz] • weights: per-channel Gi (Default: Table 3 by channel count) • momentary_step [s] (Default: 0.01), short_term_step [s] (Default: 0.1) • oversample: true-peak factor (Default: None → reaches 192 kHz)	res = broadcast.program_loudness(x, fs) • ProgramLoudnessResult
integrated_loudness	function	Programme (integrated) loudness with the two-stage gate (BS.1770-5 Annex 1). • x, fs [Hz] • weights (Default: Table 3 by channel count) Absolute gate −70 LKFS, relative −10 LU	integrated_loudness(x, fs) # LUFS
loudness_range	function	Loudness range LRA (EBU Tech 3342). • short_term_loudness: S readings [LUFS] at ≥ 10 Hz Cascaded gate (−70 LUFS abs, −20 LU rel), 10th-95th percentile spread	loudness_range(res.short_term) # LU
true_peak_level	function	True-peak level (BS.1770-5 Annex 2). • x (1.0 = 0 dBFS), fs [Hz] • oversample: factor ≥ 1 (Default: None → smallest reaching 192 kHz, 4 at 48 kHz)	true_peak_level(x, fs) # dBTP Scalar for 1D, per-channel array for 2D
k_weighting	function	Apply the two-stage K-weighting pre-filter (BS.1770-5 Annex 1). • x, fs [Hz] Spherical-head shelf + RLB high-pass	y = broadcast.k_weighting(x, fs)
k_weighting_coefficients	function	K-weighting biquads (Tables 1-2). • fs [Hz] (≥ 16 kHz) Verbatim tables at 48 kHz; analog-prototype redesign elsewhere	(b1, a1), (b2, a2) = broadcast.k_weighting_coefficients(fs)
k_weighting_response	function	K-weighting magnitude frequency response (BS.1770-5 Annex 1). • fs [Hz] (≥ 16 kHz, Default: 48000) • frequencies [Hz] (Default: None → n log points 10 Hz→Nyquist), n (Default: 512) Evaluates the Table 1-2 biquads with freqz	k_weighting_response().plot() • KWeightingResponse
channel_weight	function	Position-dependent channel weight Gi (BS.1770-5 Annex 3, Table 4). • azimuth [deg], elevation [deg] (Default: 0) 1.41 for mid-layer side positions, 1.0 elsewhere	channel_weight(110, 0) # 1.41
DEFAULT_CHANNEL_WEIGHTS	dict	Table 3 weights by channel count. 1/2/5/6 channels; 5.1 order L, R, C, LFE, Ls, Rs with the LFE at 0.0 (excluded)	DEFAULT_CHANNEL_WEIGHTS[6]
ProgramLoudnessResult	dataclass	EBU Mode measurement result. • integrated [LUFS], loudness_range [LU], true_peak [dBTP] • momentary / short_term series with momentary_time / short_term_time [s] • max_momentary / max_short_term [LUFS] • relative_threshold, lra_low / lra_high [LUFS] • true_peak_per_channel [dBTP], channel_weights, fs • .plot(): M/S over time with I and LRA annotated • .report(path, *, tolerance='qc'/'live'): R 128 fiche (±0.2 LU item i / ±1.0 LU item h)	res.integrated, res.loudness_range
KWeightingResponse	dataclass	K-weighting magnitude frequency response (BS.1770-5 Annex 1). • frequencies [Hz], magnitude_db (combined) [dB] • shelf_db (stage 1, +4 dB shelf), highpass_db (stage 2, RLB) [dB] • fs [Hz] • .plot(): magnitude vs frequency (log axis) with the two stages	k_weighting_response().magnitude_db
quasi_peak_meter	function	ITU-R BS.468-4 clause 2 quasi-peak reading of a record, in dBqps. • x: 1-D record, or a Signal • fs [Hz] • weighted: run the clause 1 network first (Default: True; False is the clause 2.4 mode) • reference: level reference in the record's own unit (Default: None → 0.775 V; required for a calibrated Signal, whose samples are pascals) Reading = the maximum of the needle over the record, so the record must include the decay	res = broadcast.quasi_peak_meter(x, fs) • QuasiPeakResult
QuasiPeakResult	dataclass	Quasi-peak reading of one record (BS.468-4 clause 2). • reading (record's unit), level_db, reference • trace: the needle, sample for sample with the record • fs [Hz], weighted • .times [s], .level_unit: 'dBqps' only against the 0.775 V of clause 2.6 • .plot(): the trace with the reading marked • no .report(): BS.468-4 prescribes no report format	res.reading, res.level_unit
verify_quasi_peak_dynamics	function	Check the detector against the eleven acceptance windows of Tables 2 and 3. • fs [Hz] (Default: 48000) • keyword-only: ballistics, the chain to check (Default: BS468_BALLISTICS) Builds the clause 2.1 and 2.2 stimuli (5 kHz, integral periods, through the network) and reads each against the steady tone	rep = broadcast.verify_quasi_peak_dynamics() • QuasiPeakDynamicsResult
QuasiPeakDynamicsResult	dataclass	The eleven acceptance windows of clause 2, read on one chain. • fs [Hz], passes • worst_margin_db: smallest of the eleven margins [dB] • worst_deviation_db: largest departure from a printed reference [dB] • stimuli: eleven rows of stimulus, table, reading_percent, lower_percent, reference_percent, upper_percent, deviation_db, margin_db • no .report(): BS.468-4 prescribes no report format	rep.passes, rep.worst_margin_db
BS468_BALLISTICS / QuasiPeakBallistics	constant / dataclass	The three time constants of the quasi-peak chain, in seconds (a fit to the eleven reference readings, printed nowhere in BS.468-4). • charge 1.4096 ms, discharge 293.20 ms (the peak rectifier) • reading_device 139.99 ms (clause 2.5's symmetric indicator) The tables identify them only to within a factor of 1.88, 1.61 and 2.09 -- marginal ranges, not a box	BS468_BALLISTICS.discharge
DBQPS_REFERENCE	float	The 0.775 V r.m.s. of clause 2.6, the steady 1 kHz sine that reads 0 dBqps and fixes the scale of the whole instrument	DBQPS_REFERENCE # 0.775
sound_pressure_level	function	Underwater SPL (ISO 18405), dB re 1 µPa. • pressure: signal (1D) [Pa] • reference: p₀ (Default: 1e-6)	sound_pressure_level(p)
sound_exposure_level	function	Underwater SEL (ISO 18405/18406), dB re 1 µPa²·s. • pressure (1D) [Pa] • fs [Hz] • reference: E₀ (Default: 1e-12)	sound_exposure_level(p, fs)
peak_sound_pressure_level	function	Zero-to-peak level (ISO 18406), dB re 1 µPa. • pressure (1D) [Pa] • reference (Default: 1e-6)	peak_sound_pressure_level(p)
UNDERWATER_REFERENCE_PRESSURE / UNDERWATER_REFERENCE_EXPOSURE	float	ISO 18405 reference quantities. Reference pressure p0 = 1 µPa [Pa] and reference exposure E0 = 1 µPa²·s [Pa²·s]	UNDERWATER_REFERENCE_PRESSURE # 1e-06
underwater_to_in_air_spl / in_air_to_underwater_spl	function	Re-reference a level between 1 µPa and 20 µPa (∓26.02 dB). • level [dB] Reference change only, not an energy equivalence.	underwater_to_in_air_spl(120.0)
radiated_noise_level	function	Ship radiated noise level (ISO 17208-1), dB re 1 µPa·m. • rms_pressure_pa [Pa] • distance [m] = 20·lg(p/p₀)+20·lg(r/r₀)	radiated_noise_level(2e-6, 100.0)
hydrophone_depths	function	ISO 17208-1 hydrophone depths from depression angles_deg. • cpa_distance [m] • angles_deg (Default: (15,30,45)) [deg] = cpa·tan(angle_deg)	hydrophone_depths(100.0)
source_level_uncertainty	function	Tabulated source-level uncertainty (ISO 17208-2). • frequency [Hz] 5 dB ≤100 Hz / 3 dB 125 Hz–16 kHz / 4 dB >16 kHz	source_level_uncertainty(1000.0) # 3.0
monopole_source_level	function	Equivalent monopole source level (ISO 17208-2). • rnl: RNL [dB re 1 µPa·m] (scalar/array) • frequency [Hz] • draught D [m] • speed_of_sound (Default: 1500) [m/s] Ls = LRN + ΔL, d_s = 0.7·D	res = underwater.monopole_source_level(rnl, f, 6.0) • ShipSourceLevelResult
ShipSourceLevelResult	dataclass	Ship source-level result. • frequencies [Hz] • radiated_noise_level / surface_correction / source_level [dB] • source_depth [m] / speed_of_sound [m/s] • .plot(): RNL/Ls/ΔL vs frequency	res.source_level, res.surface_correction
single_strike_sel	function	Single-strike SEL (ISO 18406), dB re 1 µPa²·s. • pressure: one strike (1D) [Pa] • fs [Hz]	single_strike_sel(p, fs)
cumulative_sel	function	Cumulative SEL over strikes (ISO 18406). • single_sels: per-strike SELs [dB] = 10·lg(Σ 10^(SELₙ/10))	cumulative_sel([170, 176, 173])
cumulative_sel_identical	function	Cumulative SEL of N identical strikes. • sel_ss [dB] • n_strikes N (≥ 1) = sel_ss + 10·lg(N)	cumulative_sel_identical(180.0, 50)
pile_strike_metrics	function	Per-strike pile-driving metrics (ISO 18406). • pressure: one strike (1D) [Pa] • fs [Hz]	res = underwater.pile_strike_metrics(p, fs) • PileStrikeResult
sound_speed_profile	function	Sound-speed profile over a depth column. • depths (1D, increasing) [m] • temperatures_c / salinities: array or scalar • model / latitude	sound_speed_profile(z, T, S) • SoundSpeedProfile
SoundSpeedProfile	dataclass	Sound-speed profile. • depth [m] / speed_of_sound [m/s] / gradient_per_s [(m/s)/m] • model • .plot(): speed vs depth (depth down)	prof.speed_of_sound, prof.gradient_per_s
spreading_loss	function	Geometrical spreading loss, dB. • range_m [m] (scalar/array) • law: "spherical" / "cylindrical" / "practical" • transition_range [m] (for "practical")	spreading_loss(1000.0)
seawater_absorption	function	Volume absorption α, dB/km. • frequency_hz [Hz] (scalar/array) • temperature_c [°C] / salinity [ppt] / depth [m] / ph • model: "francois-garrison" (default) / "ainslie-mccolm" / "thorp"	seawater_absorption(10e3)
propagation_loss	function	Propagation loss PL = spreading + α·R, α in dB/km and R in km. • range_m [m] / frequency_hz [Hz] • law / temperature_c / salinity / depth / ph / model / transition_range	propagation_loss(r, 10e3) • PropagationLossResult
PropagationLossResult	dataclass	Propagation-loss result. • range_m [m] / pl / spreading / absorption [dB] • frequency [Hz] / absorption_coefficient [dB/km] • law / model • .plot(): PL vs range	res.pl, res.absorption_coefficient
array_directivity_index	function	Directivity index of an unshaded line array (Ainslie 2010 Eqs. 6.49–6.57). • array_length_m L, wavelength_m λ • steer_angle_rad ψ from broadside (Default: 0) • DI = 10 log₁₀(4π/δΩ); also the array gain in isotropic noise, which is the case the sonar equation assumes • 10 log₁₀(2L/λ) at broadside, 3 dB more at endfire, → 0 dB as L/λ → 0	underwater.array_directivity_index(50.0, 1.5) # 18.3
detection_threshold	function	Detection threshold at 50 % detection probability (Ainslie 2010 Eq. 11.22). • false_alarm_probability p_fa, in (0, ½) • DT = 10 log₁₀(log₂[1/(2 p_fa)]) − 0,8 dB, base two • ±0,1 dB for p_fa < 10⁻² with one-dominant-plus-Rayleigh statistics; diverges at ½	underwater.detection_threshold(1e-4) # 10.09
passive_sonar_equation	function	Passive sonar equation. • source_level / propagation_loss / noise_level [dB] • directivity_index / detection_threshold (Default: 0) SE = SL − PL − (NL − DI) − DT	passive_sonar_equation(140, 80, 60) • SonarEquationResult
active_sonar_equation	function	Active (monostatic) sonar equation. • source_level / propagation_loss / target_strength / noise_level [dB] • directivity_index / detection_threshold / reverberation_level noise-limited SE = SL − 2·PL + TS − (NL − DI) − DT; with reverberation_level → SE = SL − 2·PL + TS − RL − DT	active_sonar_equation(220, 70, 15, 60) • SonarEquationResult
SonarEquationResult	dataclass	Sonar-equation result. • mode / signal_excess / snr [dB] / figure_of_merit [dB] • propagation_loss / source_level / noise_level / directivity_index / detection_threshold [dB] • target_strength [dB or None] / reverberation_limited • .plot(): signal excess vs PL	res.signal_excess, res.figure_of_merit
critical_angle	function	Critical grazing angle φc = arccos(c1/c2), degrees. • c1 / c2 [m/s] (needs c2 > c1)	critical_angle(1500, 1650)
reflection_coefficient	function	Complex seabed Rayleigh reflection coefficient. • grazing_angle_deg [°] (scalar/array) • rho1 / c1 / rho2 / c2	reflection_coefficient(30, rho1=1000, c1=1500, rho2=1900, c2=1650)
bottom_reflection_loss	function	Seabed reflection loss BL = −20·lg|R|, dB. • grazing_angle_deg [°] • rho1 (Default: 1000) / c1 (Default: 1500) / rho2 / c2	bottom_reflection_loss(phi, rho2=1900, c2=1650) • BottomLossResult
BottomLossResult	dataclass	Seabed reflection result. • grazing_angle_deg [°] / reflection_loss [dB] • reflection_coefficient [complex] / critical_angle_deg [° or None] • .plot(): bottom loss vs grazing angle	res.reflection_loss, res.critical_angle_deg
seabed_reflection	function	Plottable seabed reflection coefficient (Rayleigh). • grazing_angle_deg [°] • rho1 (Default: 1000) / c1 (Default: 1500) / rho2 / c2	seabed_reflection(phi, rho2=1900, c2=1650) • SeabedReflection
SeabedReflection	dataclass	Seabed reflection-coefficient result. • grazing_angle_deg [°] / reflection_coefficient [complex] • magnitude |R| / bottom_loss [dB] / critical_angle_deg [° or None] • rho1 / c1 / rho2 / c2 • .plot(): |R| vs grazing angle	res.magnitude, res.critical_angle_deg
wind_noise_spectrum	function	Wenz wind noise (rule of fives), dB re 1 µPa²/Hz. • frequency_hz [Hz] / wind_speed_knots [kn]	wind_noise_spectrum(1000, 5)
thermal_noise_spectrum	function	Mellen thermal noise, dB re 1 µPa²/Hz. • frequency_hz [Hz] • temperature_c (Default: 16.85) / density (Default: 1025) / speed_of_sound (Default: 1500)	thermal_noise_spectrum(5e4)
ocean_ambient_noise	function	Composite ambient-noise spectrum (wind + thermal [+ shipping]). • frequency_hz [Hz] / wind_speed_knots [kn] • shipping [dB or None] / temperature_c / density / speed_of_sound	ocean_ambient_noise(f, wind_speed_knots=10) • AmbientNoiseResult
AmbientNoiseResult	dataclass	Ambient-noise result. • frequencies [Hz] / spectrum_level [dB re 1 µPa²/Hz] • wind / thermal / shipping [dB or None] • wind_speed_knots [kn] • .plot(): composite + components vs frequency	res.spectrum_level
ship_source_spectrum	function	Predicted ship source-level spectrum. • speed_knots (Default: 12) / length_m (Default: 100) • vessel_class (Default: "containership") / model: "jomopans-echo" (default) / "randi" / "wales-heitmeyer" • frequency_hz (Default: decidecade 10 Hz–31.5 kHz)	ship_source_spectrum(18, 300, vessel_class="containership") • ShipTrafficSpectrum
ShipTrafficSpectrum	dataclass	Ship source-spectrum result. • frequencies [Hz] / source_psd [dB re 1 µPa²/Hz at 1 m] / band_level [dB re 1 µPa m] • model / vessel_class / speed_knots / length_m • .plot(): source PSD vs frequency	res.source_psd, res.band_level
VESSEL_CLASSES	tuple	The 13 JOMOPANS-ECHO vessel classes.	"bulker" in VESSEL_CLASSES
normal_modes	function	Normal-mode propagation loss (range-independent). • frequency_hz / depths [m] / sound_speeds [m/s] • source_depth / receiver_depth [m] / ranges_m / density / bottom: "pressure-release"|"rigid" / n_depth_points	normal_modes(50, [0,200], [1500,1500], source_depth=50, receiver_depth=100) • NormalModeResult
ray_trace	function	Ray tracing and travel times through a sound-speed profile (vectorised). • depths [m] / sound_speeds [m/s] • source_depth [m] / launch_angles_deg / max_range [m] / n_steps • bathymetry: a (ranges_m, depths_m) polyline pair, or None for a level bottom	ray_trace(z, c, source_depth=1000, launch_angles_deg=[-10,0,10]) • RayTraceResult
eigenrays	function	Eigenrays connecting a traced fan's source to one receiver. • trace: a RayTraceResult / receiver_range [m] / receiver_depth [m] • bottom: "pressure-release"|"rigid"|FluidSeabed • max_arrivals (earliest kept) / n_steps	eigenrays(fan, receiver_range=5e3, receiver_depth=60) • EigenrayResult
gaussian_beams	function	Gaussian beam PL field: finite at caustics, graded into shadow zones. • frequency_hz / depths [m] / sound_speeds [m/s] • source_depth [m] / max_range [m] / range_step [m] / ranges_m / receiver_depths_m • fan: a BeamFan / bottom: "pressure-release"|"rigid"|FluidSeabed • absorption: model name|VolumeAbsorption|None / bathymetry: (ranges_m, depths_m)|None	gaussian_beams(300, [0,1000], [1500,1500], source_depth=300) • GaussianBeamResult
BeamFan	dataclass	The launch fan of gaussian_beams. • max_angle_deg (Default: 80) / n_beams (Default: overlap condition) / beam_width W₀ [m] (Default: per launch angle)	BeamFan(max_angle_deg=45.0)
FluidSeabed	dataclass	A lossy fluid seabed, passed as the bottom of eigenrays/gaussian_beams. • density ρ₂ [kg/m³] / speed_of_sound c₂ [m/s] / water_density ρ₁ (Default: 1000)	FluidSeabed(density=1800, speed_of_sound=1700)
VolumeAbsorption	dataclass	Seawater volume absorption: a model and its water. • model: "francois-garrison"|"ainslie-mccolm"|"thorp" • temperature_c [°C] / salinity [ppt] / ph	VolumeAbsorption("thorp")
parabolic_equation	function	Split-step Fourier parabolic-equation PL field. • frequency_hz / depths [m] / sound_speeds [m/s] • source_depth [m] / max_range [m] / range_step [m] / n_depth_points	parabolic_equation(50, [0,200], [1500,1500], source_depth=50) • ParabolicEquationResult
NormalModeResult	dataclass	Normal-mode result. • frequency / wavenumbers [rad/m] / mode_depths [m] / mode_functions • ranges [m] / propagation_loss [dB] / receiver_depth / source_depth • .plot(): PL vs range	res.wavenumbers, res.propagation_loss
RayTraceResult	dataclass	Ray-tracing result. • launch_angles_deg [°] (n_rays,) • ranges [m] / depths [m] / travel_times [s] (all (n_rays, n_steps)) • source_depth / water_depth [m] • .plot(): ray paths	res.ranges, res.depths, res.travel_times
EigenrayResult	dataclass	Eigenray arrival list, earliest first. • launch_angles_deg / arrival_angles_deg [°] / travel_times [s] / amplitudes (complex, re 1 m) • surface_reflections / bottom_reflections / caustic_crossings (per arrival) • receiver_range / receiver_depth / source_depth / water_depth [m] • .plot(): per-path loss stems vs delay	res.travel_times, res.amplitudes
GaussianBeamResult	dataclass	Gaussian beam result. • frequency / ranges [m] / depths [m] • propagation_loss [dB] and pressure (both (n_depths, n_ranges)) • launch_angles_deg [°] / ray_ranges / ray_depths [m] / beam_widths [m] / wavefront_curvatures [1/m] (all (n_beams, n_steps)) • initial_beam_widths [m] (n_beams,) / source_depth / water_depth [m] • .plot(): PL field	res.propagation_loss, res.beam_widths
ParabolicEquationResult	dataclass	Parabolic-equation result. • frequency / ranges [m] / depths [m] • propagation_loss [dB] (n_depths, n_ranges) / source_depth • .plot(): PL field	res.propagation_loss
PileStrikeResult	dataclass	Pile-strike result. • single_strike_sel [dB re 1 µPa²·s] • peak_spl / spl [dB re 1 µPa] • pulse_duration [s] • pressure [Pa] / fs [Hz] • .plot(): waveform + cumulative energy	res.single_strike_sel, res.peak_spl
strike_sel_spectrum	function	Band-resolved single-strike SEL (ISO 18406). • pressure: one strike (1D) [Pa] / fs [Hz] • fraction: 1 or 3 (Default: 3) / limits [Hz] (Default: (10, 20000)) Parseval band split of ∫p²dt	strike_sel_spectrum(p, fs) • StrikeSelSpectrum
StrikeSelSpectrum	dataclass	Band-resolved strike SEL. • frequencies [Hz] / band_sel [dB re 1 µPa²·s] • total_sel / broadband_sel [dB] / fraction / fs [Hz] • .plot(): band SEL vs frequency	spec.frequencies, spec.band_sel
weston_propagation_loss	function	Weston shallow-water regimes: PL = −10·lg F (Ainslie §9.1.1.2). • range_m [m] / frequency_hz [Hz] / water_depth H [m] • seabed: "sand" (default) / "mud" / WestonSeabed • speed_of_sound (Default: 1500) / source_depth / receiver_depth [m] • critical_angle_deg [°] / reflection_loss_gradient_value_np_per_rad [Np/rad] overrides	weston_propagation_loss(r, 250, 50) • WestonPropagationResult
WestonPropagationResult	dataclass	Weston regime result. • range_m [m] / propagation_loss [dB re 1 m²] / propagation_factor [m⁻²] / regime • spherical / cylindrical / mode_stripping / single_mode / multipath [dB] • boundaries / frequency / water_depth / source_depth / receiver_depth / seabed • .plot(): composite loss + each regime law	res.propagation_loss, res.regime
weston_regime_boundaries	function	Range boundaries of the four Weston regimes. • frequency_hz [Hz] / water_depth [m] • seabed / speed_of_sound / critical_angle_deg / reflection_loss_gradient_value_np_per_rad	weston_regime_boundaries(250, 50) • WestonRegimeBoundaries
WestonRegimeBoundaries	dataclass	Weston regime boundaries. • spherical_to_cylindrical / cylindrical_to_mode_stripping / mode_stripping_to_single_mode [m] • critical_angle_deg [rad] / reflection_loss_gradient [Np/rad] / effective_depth [m] • cutoff_frequency [Hz] / mode_count	b.cylindrical_to_mode_stripping
reflection_loss_gradient	function	Seabed reflection loss gradient η (Ainslie Eqs. 9.51/9.53), Np/rad. • seabed: "sand" (default) / "mud" / WestonSeabed • frequency_hz [Hz] (refracting seabeds only)	reflection_loss_gradient("sand") # 0.278
critical_grazing_angle	function	ψc = arccos(c_w/c_sed), radians (0 when none exists). • sound_speed_ratio c_sed/c_w	critical_grazing_angle(1.20)
effective_depth	function	Weston effective water depth He (Ainslie Eq. 9.55), m. • water_depth [m] / frequency_hz [Hz] • seabed / speed_of_sound	effective_depth(50, 250)
waveguide_cutoff_frequency	function	Shallow-water cut-off frequency fc (Ainslie Eq. 9.60), Hz. • water_depth [m] • seabed / speed_of_sound	waveguide_cutoff_frequency(50)
loss_parameter	function	Sediment loss parameter ε = β/(40·π·lg e) (Ainslie Eq. 9.23). • attenuation_db_per_wavelength β [dB/λ]	loss_parameter(0.88) # 0.0161
WestonSeabed	dataclass	Characteristic seabed (Ainslie Table 9.1). • name / grain_size Mz / sound_speed_ratio / density_ratio • attenuation_db_per_wavelength [dB/λ] / loss_parameter ε / sound_speed_gradient_per_s c′ [s⁻¹]	WESTON_SEABEDS["sand"].density_ratio
WESTON_SEABEDS	dict	Ainslie Table 9.1 seabeds: "sand" (Mz 1.5) and "mud" (Mz 8).	WESTON_SEABEDS["mud"]
WESTON_REGIMES	tuple	Regime labels in range order. "spherical", "cylindrical", "mode-stripping", "single-mode"	WESTON_REGIMES[2]
detection_range	function	Range where the closed-form PL equals the figure of merit, m. • figure_of_merit [dB] / frequency_hz [Hz] • law / transition_range / temperature_c / salinity / depth / ph / model • max_range (Default: 500000) [m] / n_points (Default: 400)	detection_range(82.7, 50e3) • DetectionRangeResult
DetectionRangeResult	dataclass	Detection-range result. • detection_range [m] / figure_of_merit [dB] / frequency [Hz] • range_m [m] / propagation_loss [dB] / absorption_coefficient [dB/km] • law / model • .plot(): PL vs FOM with the crossing	res.detection_range
detection_range_from_curve	function	Detection range read off any computed PL curve, m. • figure_of_merit [dB] / range_m [m] / propagation_loss [dB] • crossing: "first" (default) / "last"	detection_range_from_curve(60, nm.ranges, nm.propagation_loss)
auditory_weighting	function	Marine-mammal auditory weighting W(f), dB. • frequency_hz [Hz] / group: hearing-group code • guidance: "nmfs-2024" (default) / "nmfs-2018" / "southall-2019"	auditory_weighting(1000, "LF") • AuditoryWeightingResult
AuditoryWeightingResult	dataclass	Auditory weighting result. • frequencies [Hz] / weighting W(f) [dB] / exposure_function E(f) [dB] • parameters / guidance / group / weighted_tts_onset Tw = K + C [dB] • .plot(): W(f) vs frequency	res.weighting, res.weighted_tts_onset
weighting_parameters	function	Weighting/exposure parameters of one hearing group. • group / guidance	weighting_parameters("OW", guidance="nmfs-2024") • WeightingParameters
WeightingParameters	dataclass	Weighting-function parameters. • group / guidance / description • a / b / f1_khz / f2_khz / c_db / c_db_as_printed / k_db [dB] • in_air / hearing_range_hz	p.a, p.f1_khz, p.c_db
hearing_groups	function	Hearing-group codes of a guidance version. • guidance (Default: "nmfs-2024") Codes are not portable between versions	hearing_groups("southall-2019")
WEIGHTING_GUIDANCE	tuple	Selectable guidance versions. "nmfs-2024", "nmfs-2018", "southall-2019"	WEIGHTING_GUIDANCE[0]
exposure_criteria	function	Published TTS and injury onset criteria. • group / guidance • impulsive (Default: False)	exposure_criteria("VHF", impulsive=True) • ExposureCriteria
ExposureCriteria	dataclass	TTS / injury onset criteria. • group / guidance / impulsive • tts_sel / injury_sel / tts_peak_spl / injury_peak_spl [dB or None] • injury_label ("PTS" / "AUD INJ") / sel_reference / peak_reference / source	crit.injury_sel, crit.injury_peak_spl
weighted_exposure	function	Weight a band spectrum, accumulate it and compare with the criteria. • frequency_hz [Hz] / band_sel [dB] / group • guidance / impulsive (Default: True) / n_events (Default: 1) / peak_spl [dB]	weighted_exposure(f, sel, "LF", n_events=3000) • WeightedExposureResult
WeightedExposureResult	dataclass	Weighted-exposure assessment. • frequencies [Hz] / band_sel / weighting / weighted_band_sel [dB] • unweighted_sel / weighted_sel / cumulative_sel [dB] / peak_spl [dB or None] / n_events • criteria / sel_margin / tts_margin / peak_margin / tts_peak_margin [dB or None] • exceeds_injury / exceeds_tts / guidance / group • .plot(): weighted spectrum vs criteria	res.cumulative_sel, res.exceeds_injury
group_audiogram	function	Marine-mammal group audiogram (Southall et al. 2019 Eq. 1), dB. • frequency_hz [Hz] / group • normalized (Default: False → Table 2; True → Table 3)	group_audiogram(f, "VHF") • AudiogramResult
orca_audiogram	function	Killer-whale audiogram (Ainslie Eq. 11.159), dB re 1 µPa. • frequency_hz [Hz], 500 Hz to 80 kHz Three-branch fit; 39.0 dB at 22.6 kHz, 51.2 dB at 50 kHz	orca_audiogram(50e3) • AudiogramResult
AudiogramResult	dataclass	Hearing-threshold result. • frequencies [Hz] / threshold [dB] • group / source / in_air • best_frequency [Hz] / best_threshold [dB] • .plot(): threshold vs frequency	res.threshold, res.best_threshold
audiogram_parameters	function	Fit parameters of a published group audiogram. • group / normalized	audiogram_parameters("HF") • AudiogramParameters
AudiogramParameters	dataclass	Group-audiogram fit parameters. • group / t0 [dB] / f1_khz / f2_khz [kHz] / a [dB/decade] / b • r_squared / in_air	p.t0, p.f1_khz
AUDIOGRAM_GROUPS	tuple	Groups with a published audiogram (no LF: F1 is never printed). HF, VHF, SI, PCW, OCW, PCA, OCA	"VHF" in AUDIOGRAM_GROUPS
BEST_HEARING_FREQUENCY_KHZ	dict	Southall Table 4 f0 per group (original, normalized) [kHz].	BEST_HEARING_FREQUENCY_KHZ["HF"]
ORCA_AUDIOGRAM_RANGE_KHZ	tuple	Validity range of Ainslie Eq. (11.159): (0.5, 80) kHz.	ORCA_AUDIOGRAM_RANGE_KHZ[1] # 80.0
perceived_noisiness	function	Per-band perceived noisiness (ICAO Annex 16 App. 2), noys. • spl: 24 one-third-octave band levels 50 Hz–10 kHz [dB]	perceived_noisiness(spl)
NOY_BANDS	array	The 24 noy one-third-octave bands [Hz] (ICAO Annex 16 App. 2). 50 Hz to 10 kHz	NOY_BANDS[0] # 50.0
perceived_noise_level	function	Perceived noise level PNL (ICAO Annex 16), PNdB. • spl: 24 band levels [dB] = 40 + (10/lg2)·lg N	perceived_noise_level(spl)
tone_correction	function	Tone correction C (ICAO Annex 16, slope method), dB. • spl: 24 band levels [dB] 1.5 dB threshold, cap 6⅔ dB	tone_correction(spl)
effective_perceived_noise_level	function	EPNL from a spectral time history (ICAO Annex 16), EPNdB. • spectra: (K, 24) band levels [dB] • dt (Default: 0.5) [s] • reference_time (Default: 10) [s] • procedure: 'aeroplane' (tone correction from 80 Hz, Default) / 'helicopter' (from 50 Hz, App. 2 4.3.1) EPNL = PNLTM + D	res = aircraft.effective_perceived_noise_level(spectra) • EPNLResult
epnl_from_pnlt	function	EPNL + 10 dB-down limits from a PNLT series (ICAO Annex 16). • pnlt: PNLT(k) [PNdB] • dt (Default: 0.5) [s] • reference_time (Default: 10) [s]	epnl, pnltm, kf, kl = aircraft.epnl_from_pnlt(pnlt)
EPNLResult	dataclass	EPNL result. • frequencies [Hz] / times [s] • pnl / tone_correction / pnlt [PNdB, dB] • pnltm / duration_correction / epnl • band_limits (kF, kL) • .plot(): PNL/PNLT time history	res.epnl, res.pnltm, res.band_limits
verify_aircraft_noise_system	function	IEC 61265 measurement-system verification. • directional: {f: {angle: |Δsens| dB}} (Table 1) • frequency_response / linearity / resolution filters via verify_filter_class	res = verify_aircraft_noise_system(directional=meas) • AircraftSystemComplianceResult
AircraftSystemComplianceResult	dataclass	IEC 61265 verdict on a measurement chain. • passes: conjunction of the checks, False over no measurement • checks: one entry per checked quantity, with quantity, limit, value and ok	res.passes, res.checks
sae_band_attenuation	function	One-third-octave-band atmospheric absorption (SAE ARP 5534). • frequencies [Hz] / path_length [m] • temperature_c (Default: 25) / relative_humidity_percent (Default: 70) / atmospheric_pressure_kpa (Default: 101.325) δ_B from pure-tone δ_t=α·s (α from ISO 9613-1)	sae_band_attenuation(freqs, 7620.0) • AircraftBandAttenuation
AircraftBandAttenuation	dataclass	Aircraft band-absorption result. • frequencies [Hz] / band_attenuation [dB] / midband_attenuation [dB] / coefficient [dB/m] • path_length / temperature_c / relative_humidity_percent / atmospheric_pressure_kpa • .plot(): band vs pure-tone mid-band	res.band_attenuation
npd_level	function	NPD event-level interpolation (ECAC Doc 29 §4.2). • powers / distances [m] / levels [dB] (shape P×D) • power / distance [m] linear in power (Eq. 4-3), log-linear in distance (Eq. 4-4)	npd_level(P, D, L, 16000, 1500)
npd_curve	function	NPD level over a distance sweep at one power. • powers / distances / levels • power / query_distances (Default: log sweep)	npd_curve(P, D, L, 20000) • NpdLevelResult
NpdLevelResult	dataclass	NPD distance-sweep result. • distances [m] / levels [dB] / power • table_distances / table_levels • .plot(): level vs slant distance	res.distances, res.levels
lateral_attenuation	function	Excess lateral attenuation Λ(β,ℓ) (ECAC Doc 29 Eq. 4-18/4-19). • elevation_deg β / lateral_m ℓ	lateral_attenuation(10, 500)
engine_installation_correction	function	Engine-install lateral directivity ΔI(φ) (Eq. 4-15/4-16). • depression_deg φ / mounting: "wing"|"fuselage"|"propeller"	engine_installation_correction(20, "wing")
duration_correction	function	Duration correction ΔV = 10·lg(Vref/Vseg) (Eq. 4-14). • reference_speed / segment_speed	duration_correction(82.3, 90)
noise_fraction	function	Finite-segment noise fraction ΔF (Eq. 4-20). • q [m] / segment_length λ [m] / scaled_distance dλ [m]	noise_fraction(0, 5000, 100)
impedance_adjustment	function	Acoustic-impedance adjustment of NPD data (Eq. 4-6/4-7). • temperature_c [°C] / atmospheric_pressure_kpa [kPa] = 10·lg(ρc/409.81); +0.074 dB at ISA	impedance_adjustment(15, 101.325)
start_of_roll_directivity	function	Start-of-roll rearward directivity ΔSOR (Eq. 4-22/4-24/4-25). • azimuth_deg ψ (arccos q/dSOR) / distance_m dSOR • engine: "jet"|"turboprop"; 0 ahead (ψ<90°)	start_of_roll_directivity(120, 300, "jet")
AerodromeAtmosphere	dataclass	Aerodrome air of the Doc 29 impedance adjustment (Eq. 4-6/4-7). • temperature_c [°C] (15) / atmospheric_pressure_kpa [kPa] (101.325)	AerodromeAtmosphere(25.0, 100.0)
FlightSegmentState	dataclass	What each flight-path segment is doing (one entry per segment). • ground_roll / landing_roll masks / bank ε [°] (§4.5.2)	FlightSegmentState(ground_roll=gr)
event_level	function	Single-event SEL/LAmax of a flight path at a receiver (Eq. 4-8/4-10/4-11). • path (N,5): x,y,z,power,speed / observer (x,y,z) • NPD powers / distances / exposure_levels / maximum_levels • reference_speed / mounting / metric: "exposure"|"maximum" • atmosphere: AerodromeAtmosphere / segments: FlightSegmentState	event_level(path, obs, P, D, SEL, LMAX) • FlyoverResult
noise_contour	function	Single-event noise level over a ground grid → contour. • path / NPD tables / x / y grids [m] • reference_speed / mounting / metric • atmosphere: AerodromeAtmosphere / segments: FlightSegmentState	noise_contour(path, P, D, SEL, LMAX, x=gx, y=gy) • NoiseContourResult
FlyoverResult	dataclass	Single-event result. • level [dB] / metric / segment_levels [dB] / observer • .plot(): per-segment contributions	res.level
NoiseContourResult	dataclass	Ground-grid contour result. • x / y [m] / levels [dB] (Ny×Nx) / metric • .plot(): filled contours	res.levels
load_anp_database	function	Load an EASA ANP fleet database (NPD curves + default profiles). • path: CSV export directory, or None for the bundled curated subset	db = aircraft.load_anp_database() • AnpDatabase
AnpDatabase	class	Parsed ANP database wiring real aircraft into the Doc 29 chain. • .aircraft(id) / .aircraft_ids / .npd_curves(id, op, metric) / .profile(id, op, profile_id=) • .event_level(id, obs, op) / .noise_contour(id, op, x=, y=)	db.noise_contour("747100", "departure", x=gx, y=gy) • AnpAircraft
AnpAircraft	dataclass	One ANP aircraft type: metadata + NPD/profile access + Doc 29 wiring. • aircraft_id / description / engine_type / num_engines / weight_class / mounting / npd_id • .npd_curves(op, metric) / .profile(op) / .event_level(obs, op) / .noise_contour(op, x=, y=)	db.aircraft("747100").mounting
AnpNpdCurves	dataclass	ANP NPD curves for one aircraft, metric and operation. • powers / distances [m] / levels [dB] (P×D) / metric / operation • .level(power, distance) / .plot(): level vs slant distance	db.npd_curves("747100", "departure", "SEL")
AnpProfile	dataclass	ANP default fixed-point trajectory as a Doc 29 flight path. • path (N,5): x,y,z,power,speed [SI] / ground_roll / landing_roll masks • .plot(): altitude vs along-track distance	db.profile("747100", "departure").path
Aerodrome	dataclass	Aerodrome, weather and runway of a Doc 29 Appendix B profile. • elevation_ft / temperature_c / sea_level_pressure_inhg / headwind_kt (8) / runway_gradient_ratio • .temperature_ratio() θ / .pressure_ratio() δ / .density_ratio() σ / .pressure_altitude_ft() h (Eq. B-1..B-8)	Aerodrome(elevation_ft=1000.0, temperature_c=25.0)
PerformanceAircraft	dataclass	One aeroplane's Appendix B coefficient set. • engines N / max_static_thrust_lb / max_landing_weight_lb / .approach_weight_lb (0.9·MLW) • jet_coefficients / propeller_coefficients / aerodynamic_coefficients / .flap(op, id)	db.performance_aircraft("A320-211")
JetEngineCoefficients	dataclass	Corrected net thrust polynomial E+F·Vc+Ga·h+Gb·h²+H·T (Eq. B-9). • e [lb] / f [lb/kt] / ga [lb/ft] / gb [lb/ft²] / h [lb/°C]	JetEngineCoefficients(25000, -25, 0.3, 1e-5, 0)
PropellerEngineCoefficients	dataclass	Propeller thrust (326·η·Pp/Vt)/δ (Eq. B-12). • efficiency η / power_hp Pp per engine	PropellerEngineCoefficients(0.85, 9500)
AerodynamicCoefficients	dataclass	One flap configuration (ANP aerodynamic table). • drag_ratio R / ground_roll_coefficient B [ft/lb] / speed_coefficient C or D [kt/√lb] • a missing coefficient is None, not zero	AerodynamicCoefficients(drag_ratio=0.07)
DepartureStep	dataclass	One ANP departure procedural step (Doc 29 B6.1). • step_type: Takeoff|Climb|Accelerate|Level|Level-Accelerate / thrust_rating / flap_id • end_altitude_ft / rate_of_climb_ft_per_min / end_calibrated_airspeed_kt / energy_share_percent / distance_ft / bank_angle_deg	DepartureStep("Climb", "MaxTakeoff", "5", 1500.0)
ApproachStep	dataclass	One ANP approach procedural step (Doc 29 B7.1). • step_type: Descend|Descend-Decel|Descend-Idle|Level|Level-Decel|Level-Idle|Land|Decelerate / flap_id • start_altitude_ft / start_calibrated_airspeed_kt / descent_angle_deg / touchdown_roll_ft / distance_ft / start_thrust_percent	ApproachStep("Descend", "30", 1000.0, 135.0, 3.0)
departure_profile	function	Fly a departure procedure into a flight profile (Doc 29 B6). • aircraft / steps (first must be a Take-off) / weight_lb / aerodrome	departure_profile(acft, steps, weight_lb=W, aerodrome=apt) • FlightProfile
approach_profile	function	Fly an approach procedure into a flight profile (Doc 29 B7). • aircraft / steps (one Land step anchors distance 0) / aerodrome / weight_lb (0.9·MLW) • solved backwards from touchdown: distances are negative until the runway	approach_profile(acft, steps, aerodrome=apt) • FlightProfile
FlightProfile	dataclass	A flown procedure as an ordered Doc 29 flight profile. • points / .distance_ft / .altitude_ft / .true_airspeed_kt / .corrected_net_thrust_lb • .plot(): height and thrust vs distance	db.flight_profile("A320-211", "D", aerodrome=apt)
ProfilePoint	dataclass	One profile point in the standard's units. • distance_ft (signed) / altitude_ft AFE / true_airspeed_kt / corrected_net_thrust_lb per engine • thrust may be negative: an idle descent is drag	profile.points[0].corrected_net_thrust_lb
RotorcraftHemisphere	dataclass	Rotorcraft noise hemisphere source (ECAC Doc 32). • frequencies [Hz] / azimuth φ / polar θ [°] / levels [dB] (A×P×F) / distance (60 m) • .plot(): fore-aft directivity / .mirrored(): φ → −φ (Eq. 2)	h.levels
hemisphere_source_level	function	Interpolated source level L(fc,φ,θ) (Eq. 13-15). • hemisphere / azimuth_deg φ / polar_deg θ • energy-bilinear + nearest-bin fill	hemisphere_source_level(h, 0, 90)
hover_ring_hemisphere	function	Hemisphere from a ground-ring hover measurement (§A.3.5). • frequencies [Hz] / bearings [°] / levels (B×F) [dB] / distance (70 m) • constant-φ extension; mapping: "constant_phi"|"bearing"	hover_ring_hemisphere(f, brg, L)
hover_derived_hemisphere	function	HOGE/idle hemisphere derived from in-ground hover (Table 3). • condition: "out_of_ground_hover"|"reduced_rpm_idle"|"full_rpm_idle" • offset_db measured Approach 2 difference (default: +12/−12/−2.5 dB)	hover_derived_hemisphere(h, "full_rpm_idle")
spherical_spreading_adjustment	function	ΔLs = −20·lg(r/60) (ECAC Doc 32 Eq. 24). • distance r [m]	spherical_spreading_adjustment(600)
atmospheric_adjustment	function	ΔLa = −α(f)·(r−60) (Eq. 26/27; ISO 9613-1 α; Table 4). • frequencies [Hz] / distance r [m] • temperature_c / relative_humidity_percent / atmospheric_pressure_kpa	atmospheric_adjustment(f, 1060)
ground_effect_adjustment	function	ΔLg over an impedance plane (Chien-Soroka, Eq. 28-35). • frequencies / source_height / receiver_height / horizontal_distance • flow_resistivity σ or CNOSSOS class "A"-"H"	ground_effect_adjustment(f, 150, 1.5, 500)
flight_condition_weights	function	Hemisphere blend weights for a flight condition (NORAH2 Eq. 3-10). • database airspeeds / path_angles_deg [°] + query airspeed / path_angle_deg • Delaunay triangle blend inside the hull, nearest outside • scaling_factor Ffc (2) / triangles lookup table	flight_condition_weights(V, G, 60, 2.5)
interpolated_source_level	function	Source level between hemispheres (Eq. 8/10 over Eq. 13). • hemispheres + database conditions + query condition • azimuth_deg φ / polar_deg θ	interpolated_source_level(hs, V, G, 60, 2.5, 0, 90)
flight_path_kinematics	function	Track kinematics by central differences (Eq. 16-21). • times [s] / positions (N,3) [m] • Vg, VA, heading, curvature, bank Φ = atan(K·Vg²/g), path angle γ	flight_path_kinematics(t, xyz) • FlightPathKinematics
FlightPathKinematics	dataclass	Track kinematics result. • ground_speed / airspeed [m/s] / heading / bank_angle_deg / path_angle_deg [°] / curvature [rad/m] • .plot(): speed and angle profiles	kin.airspeed
RotorcraftAtmosphere	dataclass	Air of a rotorcraft event (Eq. 26/27). • temperature_c [°C] (25) / relative_humidity_percent [%] (70) / atmospheric_pressure_kpa [kPa] (101.325) • atmospheric_method: "iso9613"|"sae"	RotorcraftAtmosphere(atmospheric_method="sae")
RotorcraftGround	dataclass	Ground under a rotorcraft event (§A.4.3-A.4.5). • receiver_height [m] (1.2) / ground_elevation [m] / flow_resistivity σ or class • terrain (x, y, z model) + terrain_resolution [m]	RotorcraftGround(flow_resistivity="D")
RotorcraftTrackState	dataclass	Per-point flight state overriding the derived kinematics (Eq. 16-21). • airspeed / path_angle_deg / heading / bank_angle_deg, scalar or (N,)	RotorcraftTrackState(heading=180.0)
FlightConditionInterpolation	dataclass	How a flight condition blends the database hemispheres (Eq. 3-10). • scaling_factor Ffc (2) / triangles lookup table	FlightConditionInterpolation(triangles=tri)
rotorcraft_event_level	function	Single-event time history and metrics at a receiver (Doc 32 §6.1). • hemispheres + conditions / times / positions / receiver (x,y) • level_offset [dB] (Eq. 2 substitution) • ground: RotorcraftGround / atmosphere: RotorcraftAtmosphere • track_state: RotorcraftTrackState / interpolation: FlightConditionInterpolation	rotorcraft_event_level(hs, V, G, t, xyz, (x, y)) • RotorcraftEventResult
RotorcraftEventResult	dataclass	Single-event result. • times (recorded) / band_levels / a_levels [dB(A)] • la_max / sel / sel_10db / pnlt / pnltm / epnl • .plot(): LA(t) history with the 10 dB-down window	res.sel, res.epnl
rotorcraft_noise_contour	function	Single-event SEL/LASmax over a ground grid (Doc 32 §6.3). • event inputs + x / y grids [m] • metric: "exposure"|"maximum" • ground: RotorcraftGround, whose flow_resistivity / ground_elevation also take one value per grid point	rotorcraft_noise_contour(hs, V, G, t, xyz, x=gx, y=gy) • RotorcraftNoiseContourResult
RotorcraftNoiseContourResult	dataclass	Rotorcraft ground-grid contour result. • x / y [m] / levels [dB(A)] (Ny×Nx) / metric • .plot(): filled contours	res.levels
mean_ground_plane	function	Mean ground plane of a terrain section (NORAH2 Eq. 36-40). • distances / heights [m] (polyline) • continuous least squares in closed form	mean_ground_plane(d, z) • MeanGroundPlaneResult
MeanGroundPlaneResult	dataclass	Fitted plane. • slope a / intercept b [m] • .height(d) / .equivalent_height(d, z) (orthogonal) • .plot(): section + plane	res.slope
mean_flow_resistivity	function	Log-mean flow resistivity along a path (Eq. 41). • lengths [m] / resistivities [Pa·s/m²] per segment	mean_flow_resistivity(d, sig)
diffraction_attenuation	function	Pure diffraction ΔLd per band (Eq. 42-44). • path_difference δ [m] (negative allowed) / edge_height h0 [m] • edge_span e (C″, multiple edges) / capped (25 dB)	diffraction_attenuation(f, 0.5, edge_height=10)
terrain_screening_adjustment	function	Ground + screening over a vertical section (§A.4.4-A.4.5). • source / receiver (d, z) [m] / distances / heights (terrain) • flow_resistivity: value, class or per segment (Eq. 41) • clear path → mean-plane ground effect; blocked → rubber band + Eq. 45-47	terrain_screening_adjustment(f, S, R, d, z) • TerrainScreeningResult
TerrainScreeningResult	dataclass	Section result. • adjustment [dB] (replaces the flat ΔLg) / screened / path_difference δ [m] / diffraction_points • .plot(): section geometry	res.adjustment
slant_distance	function	Rotor-centre-to-microphone slant distance (IEC 61400-11). • hub_height H [m] • rotor_diameter_m D [m] • rotor_axis (Default: "horizontal" → R0 = H+D/2, Formula 1; "vertical" → R0 = H+D, Formula 2) = √(H² + R0²)	slant_distance(80.0, 100.0)
apparent_sound_power_level	function	Apparent sound power level (IEC 61400-11 Formula 26), dB re 1 pW. • band_levels: background-corrected A-weighted band SPL [dB] • r1: slant distance [m] = L_p − 6 + 10·lg(4π R1²/S0)	apparent_sound_power_level(levels, r1)
wind_turbine_tonality	function	Tonal audibility from a narrowband spectrum (IEC 61400-11), with the 9.5.2 possible-tone screening; tone lines and La anchor to the highest classified line (9.5.3/9.5.4). • levels [dB] / frequencies [Hz]: 1-D, equal length (≥ 3), strictly increasing and uniformly spaced (narrowband), covering the whole critical band • tone_frequency: optional [Hz] (≥ 20 Hz)	res = environment.wind_turbine_tonality(levels, freqs) • WindTurbineTonalityResult
WindTurbineTonalityResult	dataclass	Wind-turbine tonality result. • tone_frequency [Hz] / critical_bandwidth [Hz] • tone_level / masking_level / tonality [dB] • audibility_criterion / tonal_audibility [dB] • is_audible / has_identified_tone (False → exclude from 9.5.1 bin averaging) • .plot(): spectrum + critical band + masking	res.tonal_audibility, res.is_audible
WindTurbineNoiseWarning	warning class	IEC 61400-11 advisory. Emitted when the tonality inputs leave the standard's stated domain of validity	warnings.simplefilter('error', WindTurbineNoiseWarning)
noise_criterion	function	NC rating, clause 5.2.2 two-step (ANSI/ASA S12.2-2019). • levels: octave-band SPL [dB] (the 10 bands 16 Hz–8 kHz without frequencies) • frequencies: optional band centres [Hz] (subset allowed)	nc = room.noise_criterion(levels) • NCResult; NC-(SIL) designation, tangency when exceeded
room_criterion	function	RC Mark II rating (ANSI/ASA S12.2-2019 Annex D). • levels: octave-band SPL [dB] • frequencies: optional band centres [Hz]	rc = room.room_criterion(levels) • RCResult; LMF average + 'N'/'R'/'H'/'RH' tag
nc_curve	function	NC curve levels (Table 1). • index: NC designation 15–70 (intermediate values interpolated band by band)	nc_curve(35) # [82, 71, 60, ...] • 10 band levels [dB], 16 Hz–8 kHz
rc_curve	function	RC Mark II curve (Table D.1). • index: RC designation (value at 1000 Hz)	rc_curve(35) • −5 dB/octave line, 10 bands [dB]
NCResult	dataclass	NC rating result. • rating: NC designation (NaN outside NC-15…NC-70, see out_of_range) • sil, tangency_rating, method, label • governing_frequency: tangency band [Hz] • frequencies [Hz], levels [dB] • .plot()	nc.rating, nc.label
RCResult	dataclass	RC Mark II result. • rating: LMF rounded [dB], int • lmf: 500/1000/2000 Hz average [dB] • classification: 'N'/'R'/'H'/'RH' • reference_curve [dB], frequencies [Hz], levels [dB] • .plot()	rc.rating, rc.classification
age_threshold	function	Age-related hearing threshold distribution (ISO 7029:2017). • age: years (≥ 18) • sex: 'male'/'female' (Default: 'male') • fractile: population fractile in (0, 1) (Default: 0.5) • frequencies: subset of the 11 audiometric frequencies [Hz] (Default: None → 125–8000 Hz)	at = hearing.age_threshold(60, 'male') • AgeThresholdResult; median at 4 kHz = 20.2 dB
AUDIOMETRIC_FREQUENCIES	ndarray	The eleven audiometric frequencies of ISO 389-7:2005 Table 1 [Hz], the axis every threshold in this module is aligned with.	hearing.AUDIOMETRIC_FREQUENCIES # 125 ... 8000
FIELDS	tuple	The listening fields reference_threshold accepts: 'free-field', 'diffuse-field'.	hearing.FIELDS
SEXES	tuple	The populations age_threshold accepts (ISO 7029:2017 tabulates the two separately): 'male', 'female'.	hearing.SEXES
reference_threshold	function	Reference threshold of hearing, 0 dB HL (ISO 389-7:2005 Table 1). • field: 'free-field' or 'diffuse-field' (Default: 'free-field') • frequencies: optional subset [Hz]	t = hearing.reference_threshold() • dB SPL per audiometric frequency (1 kHz → 2.4)
RETSPL_FREQUENCIES_HZ / EARPHONES / EARPHONE_COUPLERS	constant	ISO 389-1 Tables 1 and 2: the twenty-three test frequencies, the three earphone cases the standard prints a reference level for, and the coupler each of them is calibrated on.	hearing.EARPHONE_COUPLERS['TDH 39'] # 'IEC 60303 acoustic coupler'
earphone_reference_level / hearing_level_to_coupler_spl	function	ISO 389-1:1998: what 0 dB HL is on a supra-aural earphone, and what an audiogram is worth in the coupler. • earphone_reference_level(earphone, frequencies): the RETSPL, for 'DT 48' or 'TDH 39' (Table 1, IEC 60303 coupler) or 'other supra-aural' (Table 2, IEC 60318 artificial ear) • hearing_level_to_coupler_spl(hearing_level, earphone, frequencies): the audiogram plus that reference, which is all hearing level means	hearing.earphone_reference_level('TDH 39', [1000.0]) • array([7.]) dB
AgeThresholdResult	dataclass	Age threshold distribution. • age, sex, fractile • frequencies [Hz] • median: deviation from age 18 [dB] • spread_upper / spread_lower: half-Gaussian su/sl [dB] • threshold: value at fractile [dB] • .plot()	at.median, at.threshold
nipts	function	Noise-induced permanent threshold shift (ISO 1999:2013 §6.3). • l_ex: LEX,8h [dB] • years: exposure duration (10–40 established; 1–10 extrapolated by Formula 3) • fractile: (0, 1) (Default: 0.5) • frequencies: subset [Hz] (Default: None → 500–6000 Hz)	n = hearing.nipts(95.0, 20.0) • NiptsResult; N50 at 4 kHz = 23.0 dB
htlan	function	Threshold associated with age and noise, H′ = H + N − HN/120 (ISO 1999 Formula 1). • age: years (≥ 18), sex: 'male'/'female' • l_ex: LEX,8h [dB], years • fractile: (0, 1) applied to both components (Default: 0.5) • frequencies	h = hearing.htlan(60, 'male', 95.0, 20.0) • HtlanResult; H′ at 4 kHz = 39.3 dB
NiptsResult	dataclass	NIPTS distribution. • l_ex, years, fractile • frequencies [Hz] • median: N50 (Formula 2/3) [dB] • value: NIPTS at fractile (Formula 4/5) [dB] • spread_upper / spread_lower: du/dl [dB] • .plot()	n.median, n.value
HtlanResult	dataclass	Combined HTLAN result. • age, sex, l_ex, years, fractile • frequencies [Hz] • htla: age component H [dB] • nipts: noise component N [dB] • threshold: combined H′ [dB] • .plot()	h.htla, h.nipts, h.threshold
combine_age_and_noise	function	Age and noise components combined, H′ = H + N − HN/120 (ISO 1999 Formula 1). • htla: age-associated threshold H [dB] • nipts_value: noise-induced shift N [dB] • both taken at the same population percentage; exposed for the user-supplied database B of clause 6.2.3	combine_age_and_noise(36.0, 19.0) # 49.3 • ISO 1999 Annex C: 19 − 36·19/120 = 13.3 dB of shift remains
NoiseInducedHearingLossWarning	warning class	ISO 1999 domain advisory. Emitted outside the validated domain: exposure duration beyond 1–40 yr (§6.3.1), fractile in the tails ISO calls unreliable (Q < 5 % or > 95 %, §6.3.2), or LEX,8h above the 100 dB of Annex D	warnings.simplefilter('error', NoiseInducedHearingLossWarning)
predicted_prominence	function	Predicted prominence P of an impulse (NT ACOU 112 Formula 1). • onset_rate: slope of the A/F level onset [dB/s] (> 0; qualifies above 10 dB/s) • level_difference: level rise over the onset [dB] (> 0)	predicted_prominence(50.0, 20.0) # 7.7 • P = 3 lg(rate) + 2 lg(diff)
impulse_adjustment	function	LAeq adjustment KI (Formula 2). • prominence: P	impulse_adjustment(7.7) # 4.86 • 1.8(P − 5) dB for P > 5, else 0
impulse_prominence	function	Governing prominence and adjustment of a set of impulses (clauses 7–8); only onset rates > 10 dB/s qualify (clause 4.5). • onset_rates [dB/s] • level_differences [dB]	r = environment.impulse_prominence([50, 120], [20, 15]) • ImpulseProminenceResult (P = 8.59, KI = 6.46 dB)
rating_level	function	Rating level LAr,T over a reference time (clause 8 Note 1). • laeq: LAeq,N per sub-interval [dB] • adjustment: KI,N per sub-interval [dB] • durations, reference_time: same time unit	rating_level([55, 60], [0, 4.9], [20, 10], 30) # 60.9
ImpulseProminenceResult	dataclass	Impulse-prominence verdict. • onset_rates [dB/s], level_differences [dB] • per_impulse: P of each impulse • qualifies: onset rate > 10 dB/s mask (clause 4.5) • prominence: governing (highest qualifying) P • adjustment: KI of the governing qualifying impulse [dB] (0 when none qualifies) • .plot()	r.prominence, r.adjustment
ImpulseProminenceWarning	warning class	NT ACOU 112 advisory. Emitted when a supplied level rise does not qualify as an impulse (clause 4.5)	warnings.simplefilter('error', ImpulseProminenceWarning)
impulsive_sound_adjustment	function	Objective impulsive-sound adjustment from a calibrated signal (ISO/PAS 1996-3:2022). • signal: sound pressure [Pa], fs [Hz] • dt: LpAF sampling interval [s] (10–25 ms; Default 0.02) • onset_rate_method: 'least_squares' or 'upper_half' pass-by variant • calibration_offset [dB], laeq [dB]	r = environment.impulsive_sound_adjustment(sig, fs) • ImpulsiveSoundResult (P, KI, category)
sound_pressure_level_history	function	A-weighted, F time-weighted level history LpAF (ISO/PAS 1996-3 Clause 4). • signal [Pa], fs [Hz] • dt: sampling interval [s] (10–25 ms; Default 0.02) • reference_pressure_pa [Pa], calibration_offset [dB]	t, lpaf = environment.sound_pressure_level_history(sig, fs)
detect_onsets	function	Detect LpAF onsets: start/end points, level difference and least-squares onset rate (ISO/PAS 1996-3 Clause 4, procedures a–d). • levels: LpAF [dB], dt [s] • onset_rate_method: 'least_squares' / 'upper_half'	onsets = environment.detect_onsets(lpaf, 0.02)
LevelHistory	dataclass	A frequency- and time-weighted level trace with its time axis. • times [s], levels [dB], dt [s] • unpacks as (times, levels) for the callers that always did	hist = environment.sound_pressure_level_history(sig) hist.plot() # the L_pAF trace
ImpulsiveSoundResult	dataclass	Objective impulsive-sound verdict (ISO/PAS 1996-3). • times [s], levels: LpAF [dB], dt [s] • onsets: detected ImpulseOnsets • prominence: governing P, adjustment: KI [dB] • category: 'not impulsive' / 'regular impulsive' / 'highly impulsive' • laeq, adjusted_laeq [dB] • .governing_onset, .plot()	r.adjustment, r.category
ImpulseOnset	dataclass	A single detected LpAF onset (ISO/PAS 1996-3 Clause 3). • index_start/index_end, time_start/time_end [s] • level_start/level_end [dB] • level_difference: LD = Le − Ls [dB] • onset_rate: OR [dB/s] • prominence: P, qualifies: OR > 10 dB/s	o.onset_rate, o.level_difference
ImpulsiveSoundWarning	warning class	ISO/PAS 1996-3 advisory. Emitted when no onset with a gradient above 10 dB/s is found (adjustment is 0 dB)	warnings.simplefilter('error', ImpulsiveSoundWarning)
frequency_weighted_sel	function	Frequency-weighted single-event sound exposure level from band levels (ISO 13474:2009 Equation (5)). • band_levels_db: band levels L_E(j) [dB] on the last axis; leading axes kept, so (N_atm, N_exc, n_bands) gives every replica at once • weighting_db: weighting w(j) of each band [dB] (A, C or any other)	environment.frequency_weighted_sel(bands_db, a_weighting_db) • 10 lg Σ 10^(0.1 (L_E(j) + w(j))) [dB]
replica_probabilities	function	Probability of each replica atmosphere, the product of its two class probabilities (ISO 13474 Equation (14)). • absorption_probabilities: one per atmospheric-absorption class • excess_attenuation_probabilities: one per excess-attenuation class	p = environment.replica_probabilities([1.0], p_exc) • array (N_atm, N_exc)
long_term_sel	function	Long-term average single-event sound exposure level (ISO 13474 Equation (7)), or the rating level with K (Equation (8)). • levels_db: L_E,w,k,l of each replica [dB], any shape • probabilities: same shape, summing to one • rating_adjustment_db: K for highly impulsive sound [dB] (Default: 0)	environment.long_term_sel(levels_db, p) • Annex A LT1 = 37.0 dB
turbulence_level_shift	function	Shift Δμ of each Gaussian subclass, σ² ln 10 / 20 (ISO 13474 Equation (22) in closed form). • sigma_db: standard deviation of the turbulent spread [dB]	environment.turbulence_level_shift(5.0) # 2.878 • [dB]
sel_distribution	function	Statistical distribution of the single-event sound exposure level (ISO 13474:2009 clause 5, Equations (10) to (25)). • levels_db: L_E,w of each replica atmosphere [dB], any shape • probabilities: same shape, summing to one • sigma_db: turbulent spread [dB] (Default: 5.0, the value clause 5 says is typical) • subclasses: N_sub per class (Default: 10, as Annex A)	d = environment.sel_distribution(levels_db, p) • SelDistribution
SelDistribution	dataclass	The ISO 13474 distribution: sorted classes, their boundaries and densities, and the spread density. • levels_db, probabilities, lower_bounds_db / upper_bounds_db [dB], class_densities_per_db [1/dB] (Equations (10) to (15)) • subclass_centres_db [dB], sigma_db, level_shift_db [dB], subclasses (Equations (17) to (22)) • long_term_level_db (Equation (7), LT1) and distribution_long_term_level_db (Equation (A.4), LT2) [dB] • replicas: the input replicas of each class • .class_density(x_db), .density(x_db), .exceedance(x_db) (Equation (24)), .exceedance_level(percent) (Equation (25)) • .plot(view='classes' / 'density' / 'exceedance')	d.exceedance_level(50.0) # 31.5 dB d.plot(view='exceedance')
PERCEIVED_AFFECTIVE_QUALITY_ATTRIBUTES	constant	The eight attributes of the perceived affective quality, part 2 of Method A (ISO/TS 12913-2 Figure C.4), in printed order. pleasant, chaotic, vibrant, uneventful, calm, annoying, eventful, monotonous: the variables p, ch, v, u, ca, a, e, m of ISO/TS 12913-3 Formulas (A.1) and (A.2)	environment.PERCEIVED_AFFECTIVE_QUALITY_ATTRIBUTES[0] # 'pleasant'
QuestionnaireScale	dataclass	One scale of the soundscape questionnaire as ISO/TS 12913-2 Annex C prints it (misprints included). • method ("A"/"B"), part, figure, subject • question, instruction, items • categories: left to right, scale_values: Table A.1 or B.1 • continuous: a mark anywhere on the scale (Method B)	environment.METHOD_A_SCALES[2].categories[0] # 'Strongly agree'
METHOD_A_SCALES	mapping	Method A of ISO/TS 12913-2 (C.3.1), part number to QuestionnaireScale. 1: sound source identification (Figure C.2), 2: perceived affective quality (C.4), 3: assessment of the surrounding sound environment (C.5), 4: appropriateness (C.6); scale values of ISO/TS 12913-3 Table A.1 (parts 1 and 4 run 1 to 5 from the left, parts 2 and 3 run 5 to 1)	environment.METHOD_A_SCALES[3].scale_values # (5, 4, 3, 2, 1)
METHOD_A_ALTERNATIVE_PART_1	constant	Figure C.3 of ISO/TS 12913-2, the three-source alternative to Figure C.2 for part 1. A QuestionnaireScale with the categories and scale values of Figure C.2	environment.METHOD_A_ALTERNATIVE_PART_1.items[0]
METHOD_B_SCALES	constant	The four continuous-category scales of Figure C.7, part 1 of Method B (ISO/TS 12913-2 C.3.2.3). A tuple of QuestionnaireScale: loud, unpleasant, appropriate, visit again; scale value 1 at the left-hand tick to 5 at the right-hand one (Table B.1)	environment.METHOD_B_SCALES[0].question # 'How loud is it here?'
METHOD_B_MAXIMUM_SOURCES	constant	The most sound sources a participant may rank in part 2 of Method B (ISO/TS 12913-2 C.3.2.4).	environment.METHOD_B_MAXIMUM_SOURCES # 8
PLEASANTNESS_EVENTFULNESS_RANGE	constant	Half-range of the coordinates of Formulas (A.1) and (A.2), 4 + √32 ≈ 9.66 (ISO/TS 12913-3 A.3). Dividing by it maps P and E to ±1	environment.PLEASANTNESS_EVENTFULNESS_RANGE # 9.657
method_a_scale_values	function	Scale value of a ticked Method A box (ISO/TS 12913-3 Table A.1). • positions: box counted from the left, 1 to 5 (NaN for a blank) • part: 1 to 4 (parts 2 and 3 run 5 to 1)	environment.method_a_scale_values([1, 5], part=2) # [5., 1.]
method_a_summary	function	Median and range of Method A scale values per site and item (ISO/TS 12913-3 A.2, Table A.1). • scale_values: mapping item to values, 1-D array (parts 3, 4) or (responses, items) array • part: 1 to 4 • sites: site of each response (Default: one site "all")	s = environment.method_a_summary(values, part=2, sites=sites) • MethodASummary
MethodASummary	dataclass	Ordinal statistics of Method A per site and item. • part, items, sites • medians, minima, maxima, ranges, counts: shape (sites, items) • .plot()	s.medians[0], s.ranges[0]
pleasantness_eventfulness	function	Pleasantness P and eventfulness E per respondent and per site (ISO/TS 12913-3 A.3, Formulas (A.1) and (A.2)). • scale_values: the eight attributes of part 2, mapping or (respondents, 8) array, 5 = strongly agree • sites: site of each respondent (Default: one site "all") • central_tendency: "median" (A.2) or "mean" of each attribute per site	pe = environment.pleasantness_eventfulness(values, sites=sites) • PleasantnessEventfulness
PleasantnessEventfulness	dataclass	The two soundscape dimensions of Figure A.1. • sites, attribute_values: per-site statistic of each attribute • pleasantness, eventfulness: per site, in ±9.66 • respondent_pleasantness, respondent_eventfulness, respondent_sites, respondent_counts • .normalized_pleasantness, .normalized_eventfulness: in ±1 • .plot(normalized=True, respondents=False): the model of Figure A.1	pe.normalized_pleasantness pe.plot(respondents=True)
spearman_rank_correlation	function	Spearman's rank correlation for ordinal data (ISO/TS 12913-3 A.4, Formula (A.3) untied, (A.4) tied). • x, y: paired values, at least three pairs • alternative: "two-sided" (Default), "greater", "less"	c = environment.spearman_rank_correlation(site_p, laeq) • SoundscapeCorrelation with r and its p-value (Student t, n − 2 degrees of freedom)
pearson_correlation	function	Pearson's correlation for interval data (ISO/TS 12913-3 B.3, Formulas (B.1) and (B.2), covariance over n). • x, y: paired values, at least three pairs • alternative: "two-sided" (Default), "greater", "less"	c = environment.pearson_correlation(mean_rating, laeq) • SoundscapeCorrelation
SoundscapeCorrelation	dataclass	A correlation coefficient with its probability value. • method: "spearman" / "pearson", formula: "(A.3)", "(A.4)" or "(B.1)" • coefficient, p_value, t_statistic, degrees_of_freedom, alternative • x, y, x_ranks, y_ranks (Spearman), .n • .plot()	c.coefficient, c.p_value
method_b_scale_values	function	Scale value of a mark on a Method B continuous-category scale, 1 + 4f to one decimal (ISO/TS 12913-3 B.2). • marked_fraction: position from the left-hand tick (0) to the right-hand one (1)	environment.method_b_scale_values(0.62) # 3.5
method_b_summary	function	Mean, standard deviation and confidence interval of Method B ratings per site (ISO/TS 12913-3 B.2, Table B.1). • scale_values: mapping scale to values, 1-D array or (responses, scales) array of the Figure C.7 scales • sites: site of each response • confidence_level (Default: 0.95)	b = environment.method_b_summary(values, sites=sites) • MethodBSummary
MethodBSummary	dataclass	Interval statistics of Method B per site and scale. • items, sites • means, standard_deviations (n − 1), confidence_lower / confidence_upper (Student t), medians, counts • confidence_level • .plot()	b.means[0], b.confidence_upper[0]
method_b_source_ranking	function	Median and range of the rank of each recognised sound source (ISO/TS 12913-3 B.2, ISO/TS 12913-2 C.3.2.4). • rankings: per participant, the sources listed, most noticeable first, at most eight • sites: site of each participant	r = environment.method_b_source_ranking([["traffic", "birds"], ["birds"]]) • SourceRanking
SourceRanking	dataclass	Ordinal statistics of the source ranking per site. • sources, sites, participants • median_ranks, lowest_ranks, highest_ranks, rank_ranges, mentions: shape (sites, sources) • .plot()	r.sources, r.median_ranks[0]
SoundscapeParticipants	dataclass	ISO/TS 12913-2 A.2 a) to e): how the participants were selected, residents or visitors, lay or expert, age and gender distribution, other relevant information. Every item required; an empty one raises naming its clause	environment.SoundscapeParticipants(selection="...", ...)
SoundscapeAcousticEnvironment	dataclass	ISO/TS 12913-2 A.3 a) to h): the studied acoustic environment. • environment_type: "real", "recorded", "virtual" • sound_sources, weather_and_wind, time_of_year_and_day, measurement_points • measurement_results: the seven results of A.3 f) by symbol (LAeq,T, LCeq,T, LAF5,T, LAF95,T, N5, N95, Nrmc) • site_description (field or recorded), recording_and_reproduction (recorded or virtual)	environment.SoundscapeAcousticEnvironment(..., measurement_results=bi.reporting_results())
SoundscapeDataCollection	dataclass	ISO/TS 12913-2 A.4 a) to e): how the perception data were collected. • methods, questions, language, instrument_copy (required) • rating_scale_construction, behaviour_observation (when the study used them)	environment.SoundscapeDataCollection(methods="...", ...)
SoundscapeReport	dataclass	The minimum reporting requirements of ISO/TS 12913-2 Annex A (normative), checked when built. • participants (A.2), acoustic_environment (A.3), data_collection (A.4)	environment.SoundscapeReport(participants, environment_record, collection)
BINAURAL_PARAMETERS	mapping	ISO/TS 12913-3 Table D.1, row name to BinauralParameter. "sound_pressure_level", "loudness", "sharpness", "tonality", "roughness", "fluctuation_strength"	environment.BINAURAL_PARAMETERS["loudness"].metrics
BinauralParameter	dataclass	One row of Table D.1. • parameter, metrics (the printed symbols), average_allowed, reference	environment.BINAURAL_PARAMETERS["roughness"].reference # '[32]'
binaural_indicators	function	Every metric of ISO/TS 12913-3 Table D.1 at each ear, with the representative value of D.2. • x: equalized binaural recording (2, samples), left first, or a two-channel Signal • fs [Hz], calibration_factor (to Pa) • field: "free" (Default) or "diffuse" • parameters: rows of Table D.1 (Default: all) • sharpness S5/Saverage/S95 reported as not implemented; recordings under 3 min or 44.1 kHz emit SoundscapeWarning	bi = environment.binaural_indicators(x, 48000, parameters=("sound_pressure_level", "loudness")) • BinauralIndicators
BinauralIndicators	dataclass	The binaural analysis of a recording. • metrics: symbol to BinauralMetric, in Table D.1 order • not_implemented: symbol to the reason • parameters, fs [Hz], duration_s [s], field • .representative(symbol), .reporting_results() (ISO/TS 12913-2 A.3 f)) • .plot(parameter=None)	bi.representative("LAeq,T") bi.plot(parameter="loudness")
BinauralMetric	dataclass	One metric at both ears. • symbol, parameter, left, right, unit, method • .representative: the higher ear (D.2), .mean: their average	bi.metrics["N5"].representative
SoundscapeWarning	warning class	ISO/TS 12913-2 Annex D advisory. Emitted for a recording shorter than the 3 min of D.3 or sampled below the 44.1 kHz of D.6	warnings.simplefilter('error', SoundscapeWarning)
multiple_shock_assessment	function	Full multiple-shock assessment from seat acceleration (ISO 2631-5:2018). • acceleration: vertical seat az(t) [m/s²], fs [Hz] • start_age: years, years: exposure years, days_per_year • exposure_time / measurement_time: scale Dz to a daily dose (Default: None) • sex: 'male'/'female' (Default: 'male') • mz: MPa per m/s² (Default: sex-specific)	res = vibration.multiple_shock_assessment(az, fs, start_age=25, years=30, days_per_year=220) • MultipleShockResult
seat_to_spine_transfer	function	Seat-to-spine transfer function H(ω) (clause 5.2 Formula 1). • frequencies [Hz]	H = vibration.seat_to_spine_transfer(freqs) • Complex response; unity at 0 Hz
spinal_response	function	Vertical spinal response Az(t) (Formula 2). • acceleration: seat az(t) [m/s²] • fs [Hz]	Az = vibration.spinal_response(az, fs) • Same length as the input [m/s²]
response_peaks	function	Positive response peaks Az,i (clause 5.3). • response: Az(t)	peaks = vibration.response_peaks(Az) • Maxima between zero crossings [m/s²]
dose_from_peaks	function	Acceleration dose Dz from peaks (Formula 3). • peaks: Az,i [m/s²]	dz = vibration.dose_from_peaks(peaks) • Dz = 1.07 (Σ Az,i⁶)^(1/6) [m/s²]
acceleration_dose	function	Acceleration dose Dz from a time history (Formulas 2 + 3). • acceleration: seat az(t) [m/s²], fs [Hz]	dz = vibration.acceleration_dose(az, fs) • Dz [m/s²]
daily_dose	function	Daily dose Dzd (Formula 4). • dose: Dz [m/s²] • exposure_time td / measurement_time tm: same unit	daily_dose(4.0, 8.0, 2.0) # 5.04 • Dz (td/tm)^(1/6) [m/s²]
daily_dose_multi	function	Daily dose from several exposure conditions (Formula 5). • doses: Dz,j [m/s²] • exposure_times / measurement_times: per condition	dzd = vibration.daily_dose_multi(dz, td, tm) • [Σ Dz,j⁶ (td,j/tm,j)]^(1/6) [m/s²]
compression_dose	function	Daily compressive stress Sd (Annex C Formula C.1). • daily_dose_value: Dzd [m/s²] • mz: MPa per m/s² (Default: 0.029, 82 kg male)	compression_dose(5.0) # 0.145 • Sd = mz·Dzd [MPa]
static_stress	function	Static compressive stress Sstat = mz·9.81 (Annex C). • mz (Default: 0.029)	static_stress() # 0.284 • [MPa]
ultimate_strength	function	Ultimate lumbar strength Su at an age (Formula C.4). • age: years • sex: 'male'/'female' (Default: 'male')	ultimate_strength(45.0) # 4.41 • 6.75 − Sage·age [MPa]
injury_risk	function	Cumulative injury stress variable R (Formula C.3). • daily_compression: Sd [MPa] • start_age, years, days_per_year • sex, mz	R = vibration.injury_risk(0.5, start_age=25, years=30, days_per_year=220) # 0.509
injury_probability	function	Probability of lumbar injury P(R) (Formula C.5, Weibull). • risk: R • sex (Default: 'male')	injury_probability(0.509) # 0.0389 • 1 − exp(−(R/α)^β) in 0–1
MultipleShockResult	dataclass	Multiple-shock health assessment. • acceleration_dose Dz, daily_dose Dzd [m/s²] • compression_dose Sd [MPa] • risk R, probability P(R) • sex, start_age, years, days_per_year • peaks [m/s²], risk_thresholds: R at 10/50/90 % (Table C.2) • .plot()	res.risk, res.probability
object_fraction	function	Object fraction ψ of an enclosed space (EN 12354-6 Formula 3). • object_volumes [m³] • volume: empty space V [m³]	object_fraction([12.0, 8.0], 500.0) # 0.04
hard_object_absorption	function	Equivalent absorption area of a hard object (Formula 4). • object_volume: Vobj [m³]	hard_object_absorption(8.0) # 4.0 • Aobj = Vobj^(2/3) [m²]
air_absorption_area	function	Equivalent absorption area of the air (Formula 2). • m: power attenuation of air [Np/m] • volume V [m³] • object_fraction ψ (Default: 0.0)	air_absorption_area(0.001, 500.0) # 2.0 • Aair = 4mV(1 − ψ) [m²]
equivalent_absorption_area	function	Total equivalent sound absorption area (Formula 1). • surfaces: sequence of (area, absorption_coefficient) pairs (coefficient scalar or per band) • objects: object areas Aobj [m²] (Default: ()) • air_area: Aair [m²] (Default: 0.0)	A = room.equivalent_absorption_area([(100.0, 0.03), (50.0, 0.6)], objects=[4.0], air_area=2.0) # 39.0
reverberation_time	function	Reverberation time from the absorption area (Formula 5). • absorption_area A [m²] • volume V [m³] • object_fraction ψ (Default: 0.0) • speed_of_sound c0 [m/s] (Default: 345.6 → factor 0.16)	reverberation_time(39.0, 500.0) # 2.05 • T = 55.3/c0 · V(1 − ψ)/A [s]
enclosed_space_reverberation	function	Predicted A and T per octave band (EN 12354-6 Clause 4). • surfaces: (area, per-band α) pairs • volume V [m³] • objects [m²], object_fraction ψ • air_condition: air-attenuation key, e.g. '20C_50-70' (Default: None → neglect air) • frequencies [Hz] (Default: 125–8000 Hz octaves) • speed_of_sound [m/s]	res = room.enclosed_space_reverberation(surfaces, 500.0, air_condition="20C_50-70") • ReverberationResult
ReverberationResult	dataclass	Enclosed-space absorption result. • frequencies [Hz] • absorption_area: A per band [m²] • reverberation_time: T per band [s] • volume [m³], object_fraction • .plot()	res.absorption_area, res.reverberation_time
sabine_reverberation_time / eyring_reverberation_time / millington_sette_reverberation_time	function	Statistical RT prediction (T = k·V/(term + 4mV), k = 24 ln10 / c0). • volume V [m³] • surfaces: (area, α) pairs (α scalar or per band) • air_attenuation: m [Np/m] (Default: 0.0; see air_attenuation_m) • speed_of_sound (Default: 343 → k = 0.161) Term: Sabine ΣSᵢαᵢ · Eyring −S·ln(1−ᾱ) · Millington −ΣSᵢln(1−αᵢ)	eyring_reverberation_time(120.0, [(40,0.2),(40,0.2),(24,0.2),(24,0.2),(15,0.2),(15,0.2)]) # 0.548 s
fitzroy_reverberation_time / arau_puchades_reverberation_time	function	Anisotropic RT prediction for a shoebox room. • dimensions: (Lx, Ly, Lz) [m] • absorptions: mean α of the (x, y, z) wall pairs (scalar or per band) • air_attenuation [Np/m], speed_of_sound Fitzroy = area-weighted arithmetic mean of the three axial Eyring times; Arau-Puchades = geometric mean (Acustica 65, 1988)	arau_puchades_reverberation_time((8,5,3), (0.5,0.1,0.1)) # 0.812 s
mean_absorption	function	Area-weighted mean absorption ᾱ = ΣSᵢαᵢ / ΣSᵢ. • surfaces: (area, α) pairs	mean_absorption([(90.0, 0.1), (10.0, 0.9)]) # 0.18
reverberation_time_models	function	All five RT models for a shoebox room, per band. • dimensions (Lx, Ly, Lz) [m] • absorptions: (αx, αy, αz) wall-pair means (scalar or per band) • air_attenuation [Np/m], frequencies [Hz], speed_of_sound	res = room.reverberation_time_models((10,7,3.5), (ax, ay, az), frequencies=f) • ReverberationModelResult
ReverberationModelResult	dataclass	Five-model RT comparison. • frequencies [Hz] • sabine/eyring/millington_sette/fitzroy/arau_puchades: T per band [s] • volume [m³], surface_area [m²] • .models: dict keyed by name • .plot()	res.arau_puchades, res.models['Fitzroy']
apparent_dynamic_stiffness	function	Apparent dynamic stiffness s't (EN 29052-1 Formula 4). • resonant_frequency_hz fr [Hz] (scalar/array) • total_mass_per_area_kg_m2 m't [kg/m²] s't = 4π²·m't·fr² [N/m³]	apparent_dynamic_stiffness(25.0, 200.0) # 4.935e6 N/m³
plot_dynamic_stiffness_rig	function	Resonance rig to scale. • specimen_side (Default: 0.2 m), specimen_thickness (Default: 0.02 m) • load_mass (Default: 8 kg) • language	plot_dynamic_stiffness_rig()
enclosed_gas_stiffness	function	Enclosed-gas dynamic stiffness s'a (EN 29052-1 Formula 7). • thickness_m d [m] • porosity ε (0-1) • atmospheric_pressure_pa p₀ [Pa] (Default: 1e5 = 0,1 MPa) s'a = p₀/(d·ε); NOTE ≈ 111/d MN/m³ (d in mm)	enclosed_gas_stiffness(0.020, 0.9) # 5.56e6 N/m³
installed_dynamic_stiffness	function	Installed s' by airflow resistivity (EN 29052-1 clause 8.2). • apparent_stiffness_n_m3 s't [N/m³] • airflow_resistivity_kpa_s_m2 r [kPa·s/m²], by name only • gas_stiffness_n_m3 s'a [N/m³] (Default: None; required below r = 100) r≥100 → s't · 10≤r<100 → s't+s'a · r<10 → s't if s'a negligible else nan (warns)	installed_dynamic_stiffness(20e6, airflow_resistivity_kpa_s_m2=50.0, gas_stiffness_n_m3=3e6) # 23e6
natural_frequency	function	Floating-floor natural frequency f0 (EN 29052-1 Formula 2). • dynamic_stiffness_n_m3 s' of the installed layer [N/m³] (scalar/array) • mass_per_area_kg_m2 m' [kg/m²] f0 = (1/2π)√(s'/m')	natural_frequency(10e6, 120.0) # 45.9 Hz
floating_floor_resonance	function	Full EN 29052-1 chain → result. • resonant_frequency_hz, total_mass_per_area_kg_m2, floor_mass_per_area_kg_m2 • airflow_resistivity_kpa_s_m2 (Default: inf), thickness_m, porosity, atmospheric_pressure_pa	res = materials.floating_floor_resonance(25.0, 200.0, 120.0) • DynamicStiffnessResult
ResilientLayer / PUBLISHED_RESILIENT_LAYERS / resilient_layer	dataclass / mapping / function	A resilient layer as a catalogue row, and the fifteen of Hopkins Table A3 (printed p. 610). • keyed '<table>/<row>': 'hopkins-2007-table-a3/<material>_<density>_<thickness>', e.g. 'hopkins-2007-table-a3/mineral_wool_rock_60_30' • optional dynamic_stiffness_n_m3 s′ of the installed layer and apparent_dynamic_stiffness_n_m3 s′t of the test specimen [N/m³], density_kg_m3, thickness_mm, plus every hedge of CatalogueRow; Table A3 prints s′ and fills only the first • .natural_frequency(mass_per_area_kg_m2, *, airflow_resistivity_pa_s_m2=None, gas_stiffness_n_m3=None) → f₀ [Hz] (Formula 2); a row with only s′t needs r [Pa·s/m²] and, below 100 kPa·s/m², s′a, and goes through clause 8.2; without r it raises CatalogueError • Measured specimens, not declared product values: design with the manufacturer's s′ to EN 29052-1	layer = materials.resilient_layer('hopkins-2007-table-a3/mineral_wool_rock_60_30') layer.natural_frequency(mass_per_area_kg_m2=100.0) # 50.3 Hz
ResilientMaterial	dataclass	One resilient material's dynamic modulus, as a page printed it. • dynamic_youngs_modulus_pa [Pa], density_kg_m3 [kg/m³], static_load_pa [Pa] (about 2 kPa, the load it was measured under) • printed as ranges, held in ranges; a layer's s' is the modulus over its thickness	rock = materials.resilient_moduli_named('rock wool')[0] rock.ranges['dynamic_youngs_modulus_pa'] # (270000.0, 330000.0) • PUBLISHED_RESILIENT_MODULI, resilient_moduli_named
PUBLISHED_RESILIENT_MODULI	mapping	Six resilient materials' dynamic moduli, keyed '<table>/<row>'. • Vigran (2008) Table 8.3 (PDF page 339): glass wool, two rock wools, polystyrene and polyurethane foam, cork • the modulus rises with the static load, by about 30 % from 2 to 4 kPa for rock wool, so it describes a layer under that load	len(materials.PUBLISHED_RESILIENT_MODULI) # 6 • ResilientMaterial, resilient_moduli_named
resilient_moduli_named	function	Every published resilient material whose name contains the text. • name: matched without case; 'rock wool' answers with both rock wools, which only their densities tell apart • empty when nothing matches	len(materials.resilient_moduli_named('rock wool')) # 2 • PUBLISHED_RESILIENT_MODULI
DynamicStiffnessResult	dataclass	Dynamic-stiffness measurement result. • apparent_stiffness/gas_stiffness/dynamic_stiffness [N/m³] • resonant_frequency [Hz], floor_mass_per_area [kg/m²] • natural_frequency [Hz] • .plot()	res.dynamic_stiffness, res.natural_frequency
DynamicStiffnessWarning	warning class	EN 29052-1 advisory. Emitted when the enclosed-gas term makes s′ unresolvable (clause 8.2)	warnings.simplefilter('error', DynamicStiffnessWarning)
convert_frf	function	Convert between any two FRFs (ISO 7626-1 Table 1). • value: complex FRF value(s) of kind source • frequency f [Hz] (scalar/array, broadcast) • source/target: receptance/mobility/accelerance/dynamic_stiffness/impedance/apparent_mass Pivots through the receptance H	convert_frf(2e-3, 80.0, "mobility", "impedance") # 500 N.s/m
FRF_UNITS	mapping	SI unit per FRF form (ISO 7626-1 Table 1, read-only). Keyed by 'receptance', 'mobility', 'accelerance', ...	FRF_UNITS['mobility'] # 'm/(N·s)'
sdof_receptance / sdof_mobility / sdof_accelerance	function	Closed-form SDOF resonator FRFs (ISO 7626-1 Table 1 / 3.1.2 definitions). • frequency f [Hz] (scalar/array) • mass m [kg], stiffness k [N/m], damping c [N·s/m] H = 1/(k − ω²m + jωc); Y = jωH; A = −ω²H	`sdof_mobility(10.07, 2.0, 8000.0, 5.0) #
resonance_frequency	function	Undamped SDOF natural frequency (closed form). • mass m [kg], stiffness k [N/m] f0 = (1/2π)√(k/m)	resonance_frequency(2.0, 8000.0) # 10.07 Hz
rigid_mass_calibration_check	function	Operational rigid-mass calibration (ISO 7626-2 7.5.2). • frf: measured FRF (complex or magnitude) • frequencies [Hz], mass m [kg] • quantity: 'accelerance' (|A| = 1/m) / 'mobility' (|Y| = 1/(ωm)) • tolerance (Default: 0.05 = ±5 %)	res = vibration.rigid_mass_calibration_check(frf, f, 10.0) • RigidMassCalibrationResult
RigidMassCalibrationResult	dataclass	Rigid-mass calibration verdict (ISO 7626-2 7.5.2). • frequencies [Hz], measured/expected/deviation per band • within_tolerance: per-band flags, passes: overall • mass [kg], quantity, tolerance	res.passes, res.deviation
random_error_percent	function	Normalized random error of an averaged FRF (ISO 7626-2 Annex A). • coherence: γ² per frequency, in (0, 1] • n_averages: n ≥ 1 ε = √((1−γ²)/(2nγ²)) [%]; 8.1.3 requires < 5 % at resonances	random_error_percent(0.8, 75) # 4.08 %
sdof_mobility_result	function	SDOF driving-point mobility → result. • frequency f [Hz] (array) • mass, stiffness, damping	res = vibration.sdof_mobility_result(f, 2.0, 8000.0, 5.0) • MobilityResult
MobilityResult	dataclass	Mobility FRF over frequency (ISO 7626-1). • frequencies [Hz], mobility Y [m/(N·s)] • driving_point: bool (i = j) • .magnitude / .phase • .to(target): any Table-1 kind • .plot():	Y(f)
transfer_stiffness_level / loss_factor	function	Transfer-stiffness level & loss factor (ISO 10846-2/-3 3.17, -1 3.8). • transfer_stiffness_level(k, reference=1.0): Lₖ = 20 lg(|k|/k₀) [dB re 1 N/m] • loss_factor(k): η = Im(k)/Re(k)	transfer_stiffness_level(1e6) # 120 dB
transfer_stiffness_direct	function	Direct method (ISO 10846-2). • blocking_force F₂,b [N] • input_displacement u₁ [m] k₂,₁ = F₂,b/u₁	transfer_stiffness_direct(5.0, 1e-6) # 5e6 N/m
transfer_stiffness_indirect	function	Indirect method (ISO 10846-3 Formula 1). • frequency f [Hz] (scalar/array) • transmissibility T = u₂/u₁ (complex) • blocking_mass m₂ [kg] • flange_mass m_f [kg] (Default: 0.0) k₂,₁ = −(2πf)²(m₂+m_f)T; warns (TransferStiffnessWarning) where |T| > 0.1 (Inequality 2: ΔL1,2 < 20 dB)	transfer_stiffness_indirect(500.0, 0.01, blocking_mass=10.0)
TRANSMISSIBILITY_LIMIT	float	Indirect-method validity limit (ISO 10846-3 6.1, Inequality 2). 0.1: |T| ≤ 0.1 ⇔ ΔL1,2 ≥ 20 dB keeps Formula (1) within 1 dB (12 %)	TRANSMISSIBILITY_LIMIT # 0.1
REFERENCE_STIFFNESS	float	Reference stiffness k0 for the level Lk [N/m] (ISO 10846-2/-3, 3.17). 1.0	REFERENCE_STIFFNESS # 1.0
blocking_force_ratio	function	Delivered/blocking force ratio (ISO 10846-1 Eq. 6). • driving_point_stiffness k₂,₂ [N/m] (complex) • termination_stiffness k_t [N/m] (complex, non-zero) F₂/F₂,b = 1/(1 + k₂,₂/k_t); within 10 % of 1 for |k₂,₂| < 0.1|k_t|	blocking_force_ratio(1e5, 1e6) # 0.909
base_transmissibility	function	Mass-loaded Kelvin-Voigt transmissibility (model). • frequency f [Hz] • mass m [kg], stiffness k [N/m], damping c [N·s/m] (Default: 0.0) T = (k+jωc)/(k−ω²m+jωc)	base_transmissibility(f, 8.0, 1e6, 120.0)
indirect_transfer_stiffness_result	function	Indirect-method sweep → result. • frequency f [Hz] (array) • transmissibility T (complex) • blocking_mass m₂ [kg], flange_mass (Default: 0.0)	res = vibration.indirect_transfer_stiffness_result(f, t, 8.0) • TransferStiffnessResult
TransferStiffnessResult	dataclass	Dynamic transfer stiffness over frequency (ISO 10846). • frequencies [Hz], transfer_stiffness k₂,₁ [N/m] • blocking_mass m₂ [kg] or None • valid: lines that meet their adequacy conditions, or None (all); the indirect method sets |T| ≤ 0.1 • .magnitude / .levels (dB re 1 N/m) / .loss_factor • .to(target): "impedance"/"apparent_mass" • .band_average(): BandAveragedStiffness over the valid lines • .plot(): Lₖ(f)	res.levels, res.band_average().levels
band_averaged_stiffness	function	One-third-octave band average of a narrow-band stiffness (ISO 10846-2 F. 6, -3 F. 7, -4 F. 11, -5 F. 6). • frequencies [Hz] (distinct), stiffness k [N/m] (complex) • valid: lines that enter the average (Default: every line) k_av = {(1/n) Σ |k(fᵢ)|²}^½ over n ≥ 5 lines per base-ten band; a band of one to four valid lines is NaN and warns (TransferStiffnessWarning)	bands = vibration.band_averaged_stiffness(f, k) • BandAveragedStiffness
BandAveragedStiffness	dataclass	One-third-octave band averages of a stiffness (ISO 10846). • nominal_frequencies (ISO 266) / center_frequencies (exact midband) [Hz] • stiffness k_av [N/m], NaN where fewer than five lines; line_counts • .determined, .levels L_k,av [dB re 1 N/m] • .plot(): the band levels, undetermined bands marked	bands.levels, bands.determined
MIN_FREQUENCIES_PER_BAND	constant	Fewest lines a band average is taken over (every part's band average: "a minimum of n = 5 frequencies"). 5	MIN_FREQUENCIES_PER_BAND # 5
TransferStiffnessWarning	warning class	ISO 10846 advisory. Emitted when an adequacy condition fails (|T| > 0.1, ΔL₁,₂ < 20 dB, unwanted input within 15 dB, m₀ over its limit) or a band holds fewer than five lines. Subclass of PhonometryWarning	warnings.simplefilter('error', TransferStiffnessWarning)
check_blocked_output / check_unwanted_input	function	Is the output blocked, and the input unidirectional? (ISO 10846-5 Inequalities 1 and 2; -2 Ineq. 1 and 3, -3 Ineq. 2 and 5, -4 Ineq. 2 and 7). • frequencies [Hz] • check_blocked_output(f, input_acceleration_level_db, output_acceleration_level_db): L_a1 − L_a2 ≥ 20 dB • check_unwanted_input(f, excitation_level_db, unwanted_level_db): ≥ 15 dB; one row per direction, the loudest decides Warns (TransferStiffnessWarning) where the condition fails	vibration.check_blocked_output(f, la1, la2).passes • LevelDifferenceCheck
LevelDifferenceCheck	dataclass	A level-difference condition judged frequency by frequency. • frequencies [Hz], difference_db, limit_db (20 or 15), condition ("blocked_output"/"unwanted_input") • .holds per frequency, .passes; no truth value • .plot()	check.holds
check_output_mass	function	Is the mass in front of the output force transducers light enough? (ISO 10846-4 Inequality 3, -2 Inequality 2). • frequencies [Hz], output_mass_kg m₀ [kg] • output_force_level_db L_F2 re 1 µN, output_acceleration_level_db L_a2 re 1 µm/s² m₀ ≤ 0.06·10^(L_F2/20)/10^(L_a2/20) kg = 0.06 |F₂|/|a₂|; warns (TransferStiffnessWarning) where it fails	vibration.check_output_mass(f, 0.4, lf2, la2).passes • OutputMassCheck
OutputMassCheck	dataclass	The output mass against its ISO 10846-4 Inequality (3) limit. • frequencies [Hz], output_mass_kg, mass_limit_kg [kg] • .holds, .passes; .inertia_ratio r = m₀|a₂|/|F₂|; .bias_bound_db −20 lg(1 − r), 0.54 dB on the bound (NOTE 1: 0.5 dB) • .plot()	check.bias_bound_db
effective_blocking_mass	function	Effective mass of a blocking mass (ISO 10846-4 Formula 6, -3 Formula 4). • frequencies [Hz] (increasing), force_n F₂, first_acceleration_m_s2 a′₁, second_acceleration_m_s2 a″₁ (phasors) • blocking_mass_kg m₂ [kg], by name only m₂,eff = |2F₂/(a′₁ + a″₁)|	vibration.effective_blocking_mass(f, F, a1, a2, blocking_mass_kg=20.0) • EffectiveBlockingMass
EffectiveBlockingMass	dataclass	Effective blocking mass and its upper limit f₃ (ISO 10846-4 Inequality 5, -3 Inequality 3). • frequencies [Hz], effective_mass_kg, blocking_mass_kg [kg] • .deviation_db 20 lg(m₂,eff/m₂); .upper_frequency_limit_hz f₃, the 1 dB crossing from 40 Hz up (None if never); .valid; .ignored_below_hz (40) • .plot()	em.upper_frequency_limit_hz
driving_point_stiffness	function	Dynamic driving-point stiffness (ISO 10846-5 Formula 3). • frequencies [Hz] (increasing; lines from 1 Hz to 20 Hz needed) • input_force_n F₁, input_acceleration_m_s2 a₁ (phasors) • output_acceleration_m_s2, unwanted_acceleration_m_s2 (Default: None): check Inequalities 1 and 2 and exclude the lines that fail k₁,₁ = −(2πf)² F₁/a₁	res = vibration.driving_point_stiffness(f, F1, a1) • DrivingPointStiffnessResult
DrivingPointStiffnessResult	dataclass	Driving-point stiffness and the transfer stiffness it stands for (ISO 10846-5 6.2, Formulas 6 and 7). • frequencies [Hz], driving_point_stiffness k₁,₁ [N/m], adequate (or None) • .levels, .loss_factor; .low_frequency_level_db (1 Hz to 20 Hz); .threshold_level_db (2 dB below) • .upper_limiting_frequency_hz f_UL (None if never reached); .valid • .band_average(): k_av(1,1) ≈ k_av(2,1) within 2 dB • .plot()	res.upper_limiting_frequency_hz, res.band_average().levels
driving_point_uncertainty	function	Uncertainty budget of a driving-point band level (ISO 10846-5 Annex B, Table B.1). • band_level_db L̂_k,av [dB re 1 N/m] • repeatability_range_db 2p [dB], by name only (u_rep = p/√3) • signal_uncertainty_db (0.3), instrumentation_uncertainty_db (0.5), test_rig_uncertainty_db (1/(2√3)), discrepancy_uncertainty_db (2/√3), linearity_uncertainty_db (1.5/(2√3)) Built on metrology.combine_uncertainty; U = 2u (B.3)	vibration.driving_point_uncertainty(118.0, repeatability_range_db=0.6).expanded_uncertainty_db • DrivingPointUncertainty
DrivingPointUncertainty	dataclass	An ISO 10846-5 Annex B budget. • budget: the metrology.UncertaintyResult, one row per Formula (B.1) input • .band_level_db, .combined_uncertainty_db (B.2), .coverage_factor (2), .expanded_uncertainty_db (B.3) • .plot(): the contributions with u and U	u.expanded_uncertainty_db
infinite_plate_impedance / infinite_plate_mobility / infinite_plate_point_mobility	function	Thin-plate point mobility Z = C√(B'm'') (Cremer Table 5.1). • bending_stiffness B' [N·m], mass_per_area m'' [kg/m²] • location: 'centre' (C=8) / 'edge' (C=3.5); real, frequency-independent	infinite_plate_impedance(1e4, 10) • float or MobilityResult
infinite_beam_mobility / infinite_beam_impedance / infinite_beam_moment_mobility / infinite_beam_point_mobility	function	Slender-beam point mobility Y = (1−j)/(4m'cB) (Cremer Table 5.1). • frequency [Hz], bending_stiffness B [N·m²], mass_per_length m' [kg/m] • location: 'centre'/'end'; 45°, ∝ ω^−½	infinite_beam_mobility(100, 200, 5) • complex or MobilityResult
beam_bending_wave_speed / plate_bending_wave_speed	function	Free bending wave speed, cB = (B ω²/m')^¼ for a beam and (B' ω²/m'')^¼ for a plate. • frequency [Hz] • beam: bending_stiffness B = EI [N·m²], mass_per_length m' [kg/m] • plate: bending_stiffness B' [N·m], mass_per_area m'' [kg/m²] • ∝ √f, so it crosses the speed of sound at fc	plate_bending_wave_speed(500.0, 4.2e3, 20.0)
longitudinal_rod_mobility	function	Point mobility of an infinite rod, Y = 1/(ρ cL S) (Cremer Table 5.1). • density ρ [kg/m³], longitudinal_wave_speed cL [m/s], cross_section_area S [m²] • Real and frequency-independent, unlike the bending mobilities	longitudinal_rod_mobility(7800.0, 5100.0, 1e-4)
longitudinal_rod_impedance / injected_power / plate_bending_stiffness	function	Rod point impedance ρcₗS; injected power W = ½|F|²Re{Y} (Cremer 5.23); plate B' = Eh³/12(1−ν²).	injected_power(10.0, y)
radiation_efficiency / coincidence_frequency	function	Plate radiation efficiency σ(f) (Hopkins 2.9, Leppington/Maidanik). • frequency [Hz], length_x/length_y [m], critical_frequency fc [Hz] • boundary: 'simply_supported'/'clamped', baffle: 'infinite'/'perpendicular' • σ → 1 above fc; fc = (c₀²/2π)√(m''/B')	radiation_efficiency(f, 1.5, 1.25, 2100) • RadiationEfficiencyResult
plot_plate_geometry	function	Baffled rectangular plate to scale. • length_x, length_y [m] • boundary (title label) • language	plot_plate_geometry(1.2, 0.8) • Also RadiationEfficiencyResult.plot_geometry()
RadiationEfficiencyResult	dataclass	Plate radiation efficiency over frequency (Hopkins 2.9.4). • radiation_efficiency σ, radiation_index 10 lg σ [dB] • critical_frequency fc, .plot(); feeds sound_power_from_vibration as ε	res.radiation_efficiency
junction_transmission	function	Bending-wave transmission of a rigid plate junction (Hopkins 5.2.1.3, Cremer 1973, Craik 1981/1996). • junction: 'X'/'T1'/'T2'/'L' • two plates' thickness h, wave_speed cL, surface_density ρs • angles_deg grid (Default: 0–90°)	junction_transmission('X', 0.1, 3200, 240, 0.1, 3200, 240) • JunctionTransmissionResult
plot_junction_geometry	function	Plate junction (L/T1/T2/X) to scale. • junction, thickness1, thickness2 [m] • language	plot_junction_geometry('X', 0.14, 0.2) • Also JunctionTransmissionResult.plot_geometry()
JunctionTransmissionResult	dataclass	Angle-resolved bending-wave transmission at a rigid junction (Hopkins 5.2.1.3). • chi, psi, critical_frequency1/critical_frequency2 fc [Hz], angles_deg, corner τ12(θ), straight τ13(θ) or None • corner_average/straight_average (Eq. 5.6), corner_reduction_index Kij (symmetric), .plot()	res.corner_average # 1/12 for identical X
junction_wave_parameters	function	Wave parameters χ, ψ of a plate pair (Hopkins 5.10/5.11). • two plates' h [m], cL [m/s], ρs [kg/m²] • χ = √(h₁cL₁/h₂cL₂) = √(fc₂/fc₁), ψ = h₂cL₂ρs₂/(h₁cL₁ρs₁)	junction_wave_parameters(0.1, 3200, 240, 0.2, 3200, 480) # (√0.5, 4)
corner_transmission_coefficient / straight_transmission_coefficient	function	τ12(θ) around a corner (Hopkins 5.12) / τ13(θ) across a straight section (5.13). • angle_rad θ [rad], chi, psi, junction • corner is 0 for χ < sinθ; straight only for 'X'/'T1'	corner_transmission_coefficient(0.0, 1.0, 1.0, 'X') # 1/8
inline_transmission_coefficient	function	Normal-incidence transmission across an in-line junction (Hopkins 5.14, Cremer 1973). • chi, psi; τ = 1 for identical plates	inline_transmission_coefficient(1.0, 1.0) # 1.0
angular_average_transmission_coefficient	function	Diffuse-field angular average ∫₀^{π/2} τ(θ)cosθ dθ (Hopkins 5.6). • chi, psi, junction, section: 'corner'/'straight'	angular_average_transmission_coefficient(1.0, 1.0, 'X') # 1/12
coupling_loss_factor	function	SEA coupling loss factor from τ (Hopkins 2.154). • transmission_coefficient τ, group_velocity cg [m/s] • junction_length L [m], frequency f [Hz], plate_area S [m²] η = cg·L·τ/(2π²fS)	coupling_loss_factor(1/12, 200, 4, 500, 10)
right_angle_transmission_coefficient	function	τ12 of a right-angle plate junction, closed form (Norton & Karczub 6.53-6.55). • thickness1, thickness2 [m]; density1/density2 [kg/m³], wave_speed1/wave_speed2 [m/s] • incidence: 'random' (Default, Eq. 6.55) / 'normal' (Eq. 6.53) • feed to coupling_loss_factor with cg = 2cB to get Norton Eq. (6.52)	right_angle_transmission_coefficient(0.003, 0.0055, density1=2700, density2=2700, wave_speed1=5432, wave_speed2=5432)
point_connection_coupling_loss_factor	function	η12 of plates joined at N points (bolts/rivets/spot welds) (Norton & Karczub 6.56). • frequency [Hz], n_connections N • thickness1/thickness2 [m], surface_density1/surface_density2 [kg/m²], wave_speed1/wave_speed2 [m/s], plate_area1 S1 [m²] • falls as 1/f (a line junction falls as 1/√f)	point_connection_coupling_loss_factor(f, 12, thickness1=0.003, ...)
power_injection_clf	function	Experimental SEA: CLFs from one drive plus reciprocity (Norton & Karczub 6.8/6.15). • frequency [Hz], energy1/energy2 E = M⟨v²⟩ [J] • internal_loss_factor1/2, modal_density1/2 [1/Hz] • η12 = η2·E2/(E1 − E2·n1/n2), η21 = η12·n1/n2	power_injection_clf(500, 0.087, 0.013, 4.4e-3, 2.4e-3, 0.557, 0.606) • PowerInjectionResult
power_injection_matrix	function	Two-drive power-injection inversion (no reciprocity assumed). • frequency [Hz], energies (2, 2, nb) [J], input_powers (2, nb) [W] • returns all four loss factors; reciprocity becomes a check	power_injection_matrix(f, e, p) • PowerInjectionResult
PowerInjectionResult	dataclass	Loss-factor budget of a two-subsystem SEA model. • coupling_loss_factor12/21, internal_loss_factor1/2, energy1/2, input_power1/2, modal_density1/2, method • input_power, dissipated_power, transmitted_power, coupling_strength η12/η1, modal_density_ratio, .plot()	res.coupling_loss_factor12, res.input_power
flat_plate_modal_density / bar_modal_density / beam_modal_density	function	Modal densities of structural elements (Norton & Karczub 6.23-6.25). • plate: n = S√12/(2cL·t) (equals π·S·fc/c₀² exactly) • bar: n = 2L/cL; beam: n = L(ρA/EI)^¼/√(2πf) (falls with f)	flat_plate_modal_density(8.73, 0.005, 5432.3) # 0.557 /Hz
cylindrical_shell_modal_density / ring_frequency	function	Average modal density of a thin-walled cylinder (Norton & Karczub 6.26-6.29, Szechenyi). • frequency [Hz], area S [m²], thickness t [m], mean_radius a [m], longitudinal_wave_speed cL [m/s], band: 'octave'/'third' • three regimes about fr = cL/(2πa)	cylindrical_shell_modal_density(500, 9.42, 0.003, 0.75, 5432.3)
seat_factor / seat_transmission / SeatTransmissionResult	function / dataclass	What a seat does to the vibration under it (ISO 10326-1 Formula (2)). • seat_factor(a_wS, a_wP): the SEAT factor, below 1 when the seat attenuates • seat_transmission(seat_runs, platform_runs): one test from its runs, each set averaged only if it holds the ± 5 % of 10.2.1 • .seat_factor, .attenuates, .corrected_acceleration(intended), .plot()	vibration.seat_transmission([0.72, 0.70, 0.71], [1.02, 1.00, 0.99]).seat_factor • 0.708
corrected_seat_acceleration / resonance_transmissibility	function	The corrected seat magnitude and the resonance ratio (ISO 10326-1 Clause 10). • corrected_seat_acceleration(a_wS, a_wP, intended): the seat magnitude scaled to the input the test intended (10.2.3, Formula (4); the printed Formula (3) is an identity, see the errata) • resonance_transmissibility(a_S, a_P): Formula (5), the damping test at the suspension resonance	vibration.corrected_seat_acceleration(0.70, 1.00, 1.10) # 0.77
mean_of_test_runs / RUN_AGREEMENT_TOLERANCE / TEST_RUNS	function / constant	The three runs a seat test is made of (ISO 10326-1 10.2.1, 10.3). • the arithmetic mean of runs that agree within ± 5 % of it, and a refusal when they do not • tolerance= tightens the band for an application standard that asks for less	vibration.mean_of_test_runs([1.02, 1.00, 0.99]) # 1.003
DAMPING_TEST_MASS_KG / DAMPING_TEST_MASS_TOLERANCE / ACTIVE_DAMPING_TEST_MASS_KG / UNITY_TRANSMISSION	constant	The masses and the neutral value of ISO 10326-1. • 75 kg ± 1 % of inert mass for the damping test (10.3) • 60 kg where the suspension is actively damped (9.5.1) • 1, the ratio at which the seat passes the vibration through unchanged, which says nothing about it being rigid; Clause 11 leaves acceptance values to the application standard	vibration.DAMPING_TEST_MASS_KG # 75.0
guideline_velocity / BUILDING_CLASSES	function / constant	Guideline peak velocity for a structural-vibration assessment (DIN 4150-3 Tables 1 and 3). Keeping to a value meets the standard's criterion and certifies nothing; exceeding one is not a finding of damage • building_class: 'commercial', 'residential' or 'sensitive' • frequency [Hz], needed only at the foundation for short-term vibration • location: 'foundation' or 'top_floor'; duration: 'short_term' or 'long_term' • massive_structure=True doubles the commercial row (5.1)	vibration.guideline_velocity('residential', 30) # 10.0 mm/s
pipeline_guideline_velocity / PIPELINE_MATERIALS	function / constant	Guideline peak velocity on a buried pipeline (DIN 4150-3 Table 2). • material: 'welded_steel' 100, 'concrete_or_flanged_metal' 80, 'masonry_or_plastic' 50 mm/s • duration='long_term' halves them, which is the reduction 6.3 allows	vibration.pipeline_guideline_velocity('welded_steel') # 100.0
assess_building_vibration / DamageAssessment	function / dataclass	One measured peak velocity against its guideline value. • velocity_mm_s plus the same building_class, frequency_hz, location and duration • .guideline_mm_s, .ratio, .within_guideline, .plot() drawing Bild 1 with the measurement on it	vibration.assess_building_vibration(4.2, building_class='residential', frequency_hz=18).ratio # 0.6
bending_stress / storey_fundamental_frequency	function	From a velocity to a stress, and the storey estimate (DIN 4150-3 6.2 and 6.4). • bending_stress(peak_velocity_m_s, dynamic_modulus_pa=, density_kg_m3=, load_ratio=, mode_factor=), Formula (1); note the m/s • storey_fundamental_frequency(n) = 10/n Hz, from about five storeys up	vibration.bending_stress(0.01, dynamic_modulus_pa=3e10, density_kg_m3=2400) • 1.47e5 Pa
BuildingDamageWarning	warning class	A DIN 4150-3 rule used outside the range the standard offers it for. Emitted by storey_fundamental_frequency below STOREY_FREQUENCY_MIN_STOREYS, where 10/n is an extrapolation rather than the rule of 6.4	warnings.simplefilter("error", vibration.BuildingDamageWarning)
foundation_guideline_curve	function	Bild 1 as two arrays, ready to plot. • building_class, and frequency to sample elsewhere than the four printed corners • returns (frequency_hz, guideline_mm_s)	vibration.foundation_guideline_curve('sensitive') • (1, 10, 50, 100) Hz, (3, 3, 8, 10) mm/s
SHORT_TERM_FOUNDATION_MM_S / FOUNDATION_FREQUENCIES_HZ / SHORT_TERM_TOP_FLOOR_MM_S / LONG_TERM_TOP_FLOOR_MM_S / PIPELINE_MM_S	constant	The three printed tables of DIN 4150-3, as data. • Table 1 at the foundation, by class, at 1, 10, 50 and 100 Hz • Table 1 in the topmost floor plane: 40 / 15 / 8 mm/s • Table 3, long-term: 10 / 5 / 2.5 mm/s; Table 2, pipelines: 100 / 80 / 50 mm/s	vibration.SHORT_TERM_FOUNDATION_MM_S['residential'] # (5.0, 5.0, 15.0, 20.0)
FLOOR_VERTICAL_MM_S / MASSIVE_STRUCTURE_FACTOR / PIPELINE_LONG_TERM_FACTOR / BENDING_STRESS_CONSTANT / STOREY_FREQUENCY_NUMERATOR_HZ / STOREY_FREQUENCY_MIN_STOREYS	constant	The numbers DIN 4150-3 prints in sentences rather than in tables. • 20 mm/s vertical for a floor (5.2); the factor 2 for massive engineering structures (5.1) • the 50 % of 6.3; the 1,73 of Formula (1) • the 10 Hz and the five storeys of 6.4	vibration.FLOOR_VERTICAL_MM_S # 20.0
fundamental_period / fundamental_frequency / PERIOD_MODELS	function / constant	Empirical fundamental translation mode of a building (ISO 4866 Annex D). • fundamental_period returns T in seconds, fundamental_frequency returns f in hertz • model: 'storeys' (T = 0,1 n), 'height' (T = k₁h), 'height_width' (T = k₂h/√b), 'slenderness' (T = k₃(h/√b)√(h/(h+b))) • storeys, height_m, width_m as the model needs them, and only those: an argument the form does not use is refused • coefficient defaults to the middle of the range D.2 prints for that form	vibration.fundamental_frequency('height_width', height_m=60, width_m=20) • 0.76 Hz
height_fundamental_frequency / HEIGHT_FREQUENCY_CONSTANT_HZ_M / HEIGHT_PERIOD_COEFFICIENT_S_PER_M	function / constant	The fit ISO 4866 D.2 closes with, to 163 measured buildings. • f = 46/h hertz, or T = 0,022 h seconds, scalar or array • D.3 goes on to report that computed frequencies correlate with measurement worse than this line does	vibration.height_fundamental_frequency(46) # 1.0 Hz
empirical_frequency_bounds / EMPIRICAL_FREQUENCY_TOLERANCE	function / constant	The error an empirical prediction carries (ISO 4866 D.2). • ± 50 %, which the annex calls not uncommon and typical of empirical formulae • returns (lower, upper) in hertz	vibration.empirical_frequency_bounds(2.0) # (1.0, 3.0)
estimate_fundamental_frequency / BuildingFrequencyEstimate	function / dataclass	One prediction with the coefficient and band it carries. • .frequency_hz, .period_s, .model, .coefficient, .height_m • .bounds_hz the ± 50 % band, .plot() Figure D.1 with the estimate on it	vibration.estimate_fundamental_frequency('height', height_m=46).bounds_hz
PERIOD_COEFFICIENT_RANGES / STOREY_PERIOD_COEFFICIENT_S / DAMPING_RATIO_RANGE	constant	What ISO 4866 Annex D prints as ranges rather than values, damping included: it reports measurements and offers no estimator. • k₁ 0,014 to 0,03, k₂ 0,087 to 0,109, k₃ 0,06 to 0,08 (D.2) • the storey rule as a period, 0,1 s per storey • damping measured between 0,5 % and 2,1 % of critical, with no predictor at all (D.4)	vibration.PERIOD_COEFFICIENT_RANGES['height'] # (0.014, 0.03)
ZoneBoundaries / evaluation_zone	class / function	Evaluation zones of machine vibration (ISO 20816-1 6.3.2.3). • ZoneBoundaries(a_b, b_c, c_d): the three boundaries, rising, in whichever quantity the applicable part states • evaluation_zone(magnitude, boundaries) → 'A'/'B'/'C'/'D'; a magnitude on a boundary is the top of the zone below	z = vibration.ZoneBoundaries(2.8, 7.1, 11.2) vibration.evaluation_zone(3.4, z) # 'B'
allowable_velocity	function	Frequency-shaped velocity criterion (ISO 20816-1 Figure 9, Formula C.1). • frequency f [Hz] • constant_velocity_mm_s vA [mm/s], zone_factor Zbound (see ZONE_LIMIT_FACTORS: 1 / 2.56 / 6.4) • corner_low_hz fx, corner_high_hz fy [Hz] • exponent_low k, exponent_high m (Default: 1, constant displacement below and constant acceleration above)	vibration.allowable_velocity(100, constant_velocity_mm_s=1.12, corner_low_hz=10, corner_high_hz=1000)
VectorChangeResult	dataclass	A change in vibration between two steady states (ISO 20816-1 Annex D). • magnitude the change itself, phase_deg its direction • initial / final the two states as (magnitude, phase) • magnitude_change: what a magnitude-only comparison would have reported • .plot(unit='mm/s'): the polar diagram of Figure D.1	vibration.vibration_vector_change(3, 40, 2.5, 180).plot(unit='mm/s')
vibration_vector_change	function	Change in vibration read as a vector (ISO 20816-1 Annex D). • initial_magnitude, initial_phase_deg, final_magnitude, final_phase_deg • .magnitude the real change, .magnitude_change what a magnitude comparison reports	vibration.vibration_vector_change(3, 40, 2.5, 180) • 5.17 mm/s against −0.5
TYPICAL_BOUNDARY_LADDER_MM_S / TYPICAL_ZONE_BOUNDARY_RANGES_MM_S / ZONE_LIMIT_FACTORS	constant	ISO 20816-1 Table C.1 and Annex C.2. • the ladder of 14 preferred magnitudes, 0.28 to 45 mm/s • the typical range of each boundary: A/B 0.71–4.5, B/C 1.8–9.3, C/D 4.5–14.7 mm/s • the zone factors of Formula (C.1): A 1, B 2.56, C 6.4	vibration.TYPICAL_ZONE_BOUNDARY_RANGES_MM_S['B/C'] # (1.8, 9.3)
MachineZoneLimits / INDUSTRIAL_MACHINE_ZONES	dataclass / constant	Zone boundaries of the industrial-machine tables (ISO 10816-3 Tables A.1 and A.2). • keyed by (group, support): 'group_1' above 300 kW to 50 MW, 'group_2' above 15 kW to 300 kW; 'rigid' or 'flexible' • .displacement_um and .velocity_mm_s, each a ZoneBoundaries • broad-band r.m.s. from 10 Hz to 1 kHz, or from 2 Hz below 600 r/min	vibration.INDUSTRIAL_MACHINE_ZONES['group_2', 'rigid'].velocity_mm_s.b_c # 2.8
industrial_machine_zone	function	Grade an industrial machine against its table (ISO 10816-3 5.2.3). • group, support • displacement_um and/or velocity_mm_s, whichever was measured • with both, the more restrictive grading applies • scalar in, letter out; array in, one letter per reading	vibration.industrial_machine_zone('group_2', 'rigid', displacement_um=50, velocity_mm_s=2.0) # 'C'
is_significant_change / alarm_limit / trip_limit	function	Operational limits with numbers (ISO 10816-3 5.3 and 5.4). • is_significant_change(change, zone_b_upper): more than a quarter of the upper limit of zone B, up or down • alarm_limit(baseline, zone_b_upper): that quarter above the baseline, capped at 1.25 times the limit • trip_limit(zone_c_upper): 1.25 times the upper limit of zone C	vibration.alarm_limit(0.9, 2.8) # 1.6 vibration.trip_limit(4.5) # 5.625
SIGNIFICANT_CHANGE_FRACTION / OPERATIONAL_LIMIT_HEADROOM	constant	The two fractions the operational limits are built from (ISO 10816-3 5.3, 5.4.1 and 5.4.2). • SIGNIFICANT_CHANGE_FRACTION = 0.25, of the upper limit of zone B • OPERATIONAL_LIMIT_HEADROOM = 1.25, the multiple neither limit should exceed	vibration.OPERATIONAL_LIMIT_HEADROOM * 4.5 # 5.625
GEAR_UNIT_ZONES / gear_unit_zone_boundaries	constant / function	Gear-unit zone boundaries (ISO 20816-9 Tables 2, 3 and 4). • keyed by quantity, then by rating number: 'displacement' (shaft relative peak-to-peak, µm), 'velocity' (housing r.m.s., mm/s), 'acceleration' (housing true peak, m/s²) • every row is three consecutive rungs of one ladder, with the rating as the B/C boundary • a rating with no printed row is refused, not interpolated	vibration.gear_unit_zone_boundaries('velocity', 8.0).as_tuple • (5.0, 8.0, 12.5)
GearUnitRatings / GEAR_UNIT_CLASSES	dataclass / constant	The classification of typical gear units (ISO 20816-9 Table 5). • keyed by (class, subclass): class 'I' to 'IV', subclass 'a', 'b_low' or 'b_high' • .displacement, .velocity, .acceleration; the last is None on every b) row, where the table prints no information	vibration.GEAR_UNIT_CLASSES['III', 'a'].velocity # 8.0
gear_shaft_displacement_limit / gear_housing_velocity_limit	function	The two rating curves of ISO 20816-9 Annex A. • Figure A.1: flat to 50 Hz, then 10 dB per decade down • Figure A.2: flat from 45 Hz to 1590 Hz, then 14 dB per decade down on both sides, which is Formula (C.1) of Part 1 with those corners	vibration.gear_housing_velocity_limit(3000, rating=8.0) • 5.13 mm/s
GEAR_DISPLACEMENT_CORNER_HZ / GEAR_DISPLACEMENT_SLOPE_DB_PER_DECADE / GEAR_VELOCITY_CORNERS_HZ / GEAR_VELOCITY_SLOPE_DB_PER_DECADE / GEAR_ACCEPTANCE_HEADROOM	constant	The numbers the notes under Figures A.1 and A.2 print, and the acceptance ceiling of 8.3. • 50 Hz and 10 dB per decade for displacement • 45 Hz to 1590 Hz and 14 dB per decade for velocity • 1.25, the multiple of the A/B boundary an acceptance criterion should not normally exceed	vibration.GEAR_VELOCITY_CORNERS_HZ # (45.0, 1590.0)
bearing_fault_frequencies	function	Rolling-bearing kinematic fault lines (Norton & Karczub 8.4-8.14). • speed_rpm N, n_elements Z, element_diameter d, pitch_diameter D • contact_angle_deg φ, rotating_race: 'inner'/'outer' • lines: shaft, FTF, FTF_rel, BSF, BDF, BPFO, BPFI; BPFO + BPFI = Z·fs	bearing_fault_frequencies(2000, 15, 6, 34, contact_angle_deg=12.96) # BPFO 207 Hz • FaultFrequencyResult
gear_mesh_frequencies	function	Gear-mesh frequency and sideband family (Norton & Karczub 8.3). • speed_rpm, n_teeth; harmonics, sidebands, sideband_rate [Hz] • GMF = N·fs, sidebands at k·GMF ± m·f_mod	gear_mesh_frequencies(1500, 28, sidebands=2) • FaultFrequencyResult
induction_motor_frequencies	function	Motor electrical and rotor-slot lines (Norton & Karczub 8.19/8.20). • speed_rpm, poles p, rotor_bars R; slip s or supply_frequency fe • slot_harmonics, sidebands • lines: 1x, 2x, fe, 2fe, f_slip, FP, fsh = R·fs	induction_motor_frequencies(3600, 6, 60) # 2fe 360 Hz, fsh 3600 Hz • FaultFrequencyResult
blade_pass_frequencies	function	Fan/pump blade-pass tones and lobed patterns (Norton & Karczub 8.15-8.18). • speed_rpm, n_blades; harmonics, n_vanes V, lobe_orders • BPF = n·N·fs; lobes mL = nN ± kV turning at nN·fs/mL	blade_pass_frequencies(3500, 6, n_vanes=4) # BPF 350 Hz • FaultFrequencyResult
FaultFrequencyResult / FaultLine / combine_fault_lines / shaft_rate	dataclass / function	Predicted fault lines of one machine element. • lines (name, frequency, order, family, description), shaft_rate, source • res['BPFO'], names, frequencies, orders, as_dict(), harmonics(name, n), within(low, high) • .plot(spectrum=envelope_result) overlays the lines on a measured envelope spectrum	res['BPFO'] # 207.0
wave_vibration_reduction_index	function	Wave-approach vibration reduction index Kij (Hopkins 5.116). • transmission_coefficient τ, critical_frequency_receiver fc_j [Hz] Kij = 10 lg(1/τ) + 5 lg(fc_j/f_ref), f_ref = 1000 Hz (symmetric: Kij = Kji)	wave_vibration_reduction_index(1/12, 1000.0) # 10.8 dB
velocity_level / velocity_level_from_acceleration	function	Vibratory velocity level (ISO/TS 7849-1 Eq. 3/8). • velocity_level(v, reference=5e-8): 20 lg(v/v₀) [dB] • velocity_level_from_acceleration(a_peak, f): 20 lg(â/(2πf·v₀·√2)) (sinusoidal calibration)	velocity_level_from_acceleration(9.81, 100.0) # 106.9 dB
REFERENCE_VELOCITY	float	Reference velocity v0 [m/s] (ISO/TS 7849-1). 5e-8	REFERENCE_VELOCITY # 5e-08
NORMALIZED_IMPEDANCE	float	Normalized characteristic impedance Zc,n of air [N·s/m³] (23 °C, 101,3 kPa). 411.0	NORMALIZED_IMPEDANCE # 411.0
mean_velocity_level	function	Mean surface velocity level (ISO/TS 7849-1 Eq. 10/11). • levels L_v,i [dB] • areas S_i (Eq. 11) or None → energetic mean (Eq. 10)	mean_velocity_level([60, 66, 63])
radiation_factor	function	A-weighted radiation factor ε (ISO/TS 7849 Eq. 4/8). • sound_power P [W], area S [m²] • mean_square_velocity ⟨v²⟩ [(m/s)²] • impedance Z_c (Default: 411 N·s/m³) ε = P/(Z_c·⟨v²⟩·S)	radiation_factor(3e-4, 2.0, 1e-6) # 0.365
radiated_sound_power_level	function	Sound power level from vibration (ISO/TS 7849-1 Eq. 12, -2 Eq. 15). • velocity_level L_v [dB] • area S [m²] • radiation_factor ε (Default: 1.0 → Part 1 upper limit) L_W = L_v + 10 lg(S/S₀) + 10 lg(ε) + 10 lg(411/400)	radiated_sound_power_level(80.0, 1.6)
extraneous_velocity_correction	function	Correction K1A for extraneous vibration (ISO/TS 7849-1 Table 2). • level_difference ΔLv [dB]; ΔLv≥10→0, ΔLv<3→3	extraneous_velocity_correction(6.0) # 1.0 dB
sound_power_from_vibration	function	Bundle a vibration → power determination. • velocity_level L_v per band [dB] • area S [m²], radiation_factor ε (Default: 1.0) • frequencies [Hz] or None	res = emission.sound_power_from_vibration(lv, 1.6, radiation_factor=eps, frequencies=f) • VibrationSoundPowerResult
VibrationSoundPowerResult	dataclass	Sound power radiated by surface vibration (ISO/TS 7849). • velocity_level / sound_power_level / radiation_factor per band • area S [m²], frequencies [Hz] or None • .total_level: band-summed L_W [dB] • .plot()	res.sound_power_level, res.total_level
spatial_mean_velocity_level / plate_loss_factor	function	Reception-plate helpers (EN 15657 Formula 12/13). • spatial_mean_velocity_level(levels): 10 lg(mean 10^(Lv,i/10)) [dB] • plate_loss_factor(f, Ts): η = 2.2/(f·Ts)	spatial_mean_velocity_level([78, 80, 82])
mean_free_velocity_level	function	Mean free velocity level (ISO 9611:1996 eq. (9)). • levels: free-velocity levels at the N contact points [dB re 5e-8 m/s] Energy mean over positions	mean_free_velocity_level([70, 72, 74]) # 72.3 dB
structure_borne_power_level	function	Reception-plate injected power level (EN 15657 Formula 14). • velocity_level L_v [dB re 1e-9 m/s] • frequency f [Hz], mass_per_area m [kg/m²], area S [m²] • loss_factor η > 0 L_Ws = 10 lg(2πfηmS) + L_v − 60 (plate-specific; convert via Formulae 15/17 before EN 12354-5)	structure_borne_power_level(80, 1000, 10, 1, 0.01) # 47.98 dB
equivalent_blocked_force_level / characteristic_reception_plate_power	function	Source quantities (EN 15657 Formulae 15/17). • equivalent_blocked_force_level(L_Ws_low, Y_plate): L_Fb,eq = L_Ws − 10 lg(Re Y/Y0) [dB re 1e-6 N] • characteristic_reception_plate_power(L_Fb,eq): L_Wsn = L_Fb,eq + 10 lg(Y_R,∞,low/Y0), Y_R,∞,low = 5e-6 m/(N·s)	lwsn = building.characteristic_reception_plate_power(building.equivalent_blocked_force_level(61.7, 5.34e-6))
equivalent_free_velocity_level / source_mobility_from_levels	function	Source quantities (EN 15657 Formulae 18/19). • equivalent_free_velocity_level(L_Ws_high, Y_plate): L_vf,eq [dB re 1e-9 m/s] • source_mobility_from_levels(L_vf,eq, L_Fb,eq): |Y_S,eq| [m/(N·s)]	y_s = building.source_mobility_from_levels(lvf, lfb)
reception_plate_power	function	Reception-plate determination → result (EN 15657 clause 7). • velocity_level L_v (per band), frequency [Hz] • mass_per_area, area • loss_factor η or reverberation_time Ts	res = building.reception_plate_power(lv, f, 600, 2.0, reverberation_time=0.8) • StructureBornePowerResult
StructureBornePowerResult	dataclass	Reception-plate injected structure-borne power (EN 15657). • power_level L_Ws / velocity_level / loss_factor per band • mass_per_area, area, frequencies [Hz] or None • .total_level: band-summed L_Ws [dB] • .plot()	res.power_level, res.total_level
coupling_term / coupling_term_force_source / coupling_term_velocity_source	function	Coupling term D_C (EN 12354-5 Formula 19b/c/d). • coupling_term(Ys, Yi, transfer_mobility=0): 10 lg(|Ys+Yi+Yk|²/(|Ys|·Re Yi)) • force source: 10 lg(|Ys|/Re Yi) • velocity source: −10 lg(|Ys|·Re Zi)	coupling_term(2e-4+1e-4j, 3e-5+1e-5j)
installed_structure_borne_power_level	function	Installed power (EN 12354-5 Formula 18b). • characteristic_power_level L_Ws,c [dB] (the converted EN 15657 level, not the raw Formula 14 plate power) • coupling_term D_C [dB] L_Ws,inst = L_Ws,c − D_C	installed_structure_borne_power_level(82.0, 8.5)
installed_power_from_reception_plate	function	Annex I mobility correction (EN 12354-5). • reception_plate_level L_Ws,n [dB] • receiver_mobility Y_∞,i [m/(N·s)] • plate_mobility Y_∞,rec (Default: 5e-6) L_Ws,inst = L_Ws,n + 10 lg(Y_∞,i/Y_∞,rec); with the source mobility it yields L_Ws,c	installed_power_from_reception_plate(67.6, 1.25e-6) # -6 dB
structure_borne_pressure_level_path / total_structure_borne_pressure_level	function	Path & total normalised SPL (EN 12354-5 Formula 18a/17). • path: L_Ws,inst − D_sa − R_ij,ref − 10 lg(S/S0) − 10 lg(A0/4) • total: 10 lg(Σ 10^(L/10)) over paths (axis 0)	total_structure_borne_pressure_level(path_levels)
REFERENCE_AREA	float	Reference area S0 = A0 [m²] (EN 12354-5 Formula 18a). 10.0	REFERENCE_AREA # 10.0
installed_source_prediction	function	Full installed-source prediction → result (EN 12354-5). • characteristic_power_level L_Ws,c, coupling_term D_C • paths: dicts with adjustment_term, flanking_reduction_index, element_area • frequencies [Hz] or None	res = building.installed_source_prediction(lwc, dc, paths, frequencies=f) • InstalledSourceResult
InstalledSourceResult	dataclass	Installed structure-borne sound prediction (EN 12354-5). • path_levels (paths×bands), total_level L_n,s per band • installed_power_level per band, frequencies [Hz] or None • .overall_level: band-summed total [dB] • .plot(): the cascade	res.total_level, res.overall_level
typical_element_mobility / TABLE_D1_QUANTITIES	function / dict	Mobility of typical construction elements (EN 12354-5 Table D.1). • structure: 'mass' [2πfM]⁻¹, 'bar_end' [ρcLS]⁻¹, 'beam' [7,6ρtw√(cLtf)]⁻¹, 'plate' [2,3cLρt²]⁻¹, 'pipe' [63ρtr√(cLrf)]⁻¹, 'mass_spring' • the row's own describing quantities as keywords; TABLE_D1_QUANTITIES lists them • frequency [Hz] for the four rows whose expression contains f, rejected by the other two	typical_element_mobility('plate', density=2300, longitudinal_velocity=3800, thickness=0.14) # 2.54e-6 m/(N·s)
tapping_machine_force_level / TABLE_F1_FORCE_LEVEL / TABLE_F1_OCTAVE_BANDS	function / tuple	ISO tapping machine force level (EN 12354-5 Table F.1). • octave bands 31,5 Hz to 4 kHz: 139, 142, 145, 148, 151, 154, 156, 156 dB re 1e-6 N (the caption prints "re 1 pN"; see ERRATA) • substitution source of clause D.1.2.3, low-mobility receiving structures	tapping_machine_force_level()
tapping_machine_force_level_estimate	function	Closed form printed under Table F.1 (EN 12354-5). • frequency f [Hz], bandwidth 'octave' (2,5f) or 'third' (0,8f) L_F = 10 lg(k f/10⁻¹²) dB re 1e-6 N; tracks the table only up to about 1000 Hz	tapping_machine_force_level_estimate(1000, bandwidth='third') # 149.03 dB
tapping_machine_characteristic_power_level / tapping_machine_coupling_term	function	Tapping machine as a force source (EN 12354-5 Formulae D.9a/D.9b). • power: L_Ws,c = L_F − 5 − 10 lg f (≈115 dB re 1 pW per 1/3 octave) • coupling: −10 lg(ωMYi) + 10 lg[1 + (ωMYi)²], hammer_mass M (Default: 0,5 kg)	tapping_machine_coupling_term(500.0, 1.07e-6)
structure_to_airborne_adjustment	function	Adjustment term D_sa (EN 12354-5 Formula F.3). • frequency f [Hz], critical_frequency fc [Hz], mass_per_area m [kg/m²] • radiation_factor σ (Default: 1.0) D_sa = 10 lg(400 fc σ/(m f²)); normally negative, and Formula 18a subtracts it	structure_to_airborne_adjustment(500.0, 200.0, 92.0) # -24.6 dB
multi_junction_adjustment / MINIMUM_MULTI_JUNCTION_KIJ	function / float	Multi-junction ΔK (EN 12354-5 clause F.1). • junctions ≥ 1 → 0 dB (single), 4 dB (two), 6 dB (three or more) • the resulting Kij is floored at MINIMUM_MULTI_JUNCTION_KIJ = −5.0 dB	multi_junction_adjustment(2) # 4.0
air	function	Humid air (IEC 61094-2:2009 Annex F, CIPM-2007). • temperature_c t [°C], required • static_pressure_pa p_s [Pa] (Default: None → 101 325, warns) • relative_humidity_percent H [%] (Default: None → 50, warns) • co2_mole_fraction x_c (Default: None → 0,000 4, silent)	f = fluids.air(temperature_c=23.0, static_pressure_pa=101325.0, relative_humidity_percent=50.0) • Fluid; rho = 1.1860848 kg/m³, c0 = 345.86652 m/s
Fluid	dataclass	One fluid at one state, and what its model fixed there. • temperature_c, static_pressure_pa, composition, model, validity, properties • accessors density, speed_of_sound, heat_capacity_ratio, viscosity, thermal_diffusivity, thermal_conductivity, specific_heat_capacity • closed by identity: characteristic_impedance, kinematic_viscosity, and prandtl_number unless the model printed one of its own, which wins	f.characteristic_impedance # rho c
PUBLISHED_FLUIDS	mapping	The fluid states this library has read from a published page, keyed '<table>/<row>'. • Bies 5e Table C.1 prints three fluids before its solids: air at 20 °C, fresh water at 20 °C and sea water at 13 °C • Each names its page, with the printed folio, in its model, because for a transcribed state the table is what produced it • The four airs that sit elsewhere in the tree are deliberately not here: each belongs beside the model or standard that fixes it, and gathering them would make the medium depend on three of the domains that stand on it • Not a table to look values up in: air at measured conditions is air() and sea water is sea_water()	fluids.PUBLISHED_FLUIDS['bies-2017-table-c1-fluids/fresh_water'].speed_of_sound # 1497.0 • Fluid
Gas	dataclass	One gas of a published table: the two numbers that close its state. • molar_mass_kg_mol M [kg/mol], heat_capacity_ratio γ, plus the hedges every catalogue row carries • ideal_state(temperature_c=..., static_pressure_pa=...) → Fluid, carrying the row's page in its model • a gas has no one density or speed of sound, which is why this is not a Fluid and not in PUBLISHED_FLUIDS	fluids.PUBLISHED_GASES['bies-2017-table-c2/methane'].ideal_state(temperature_c=20.0).speed_of_sound # 447.9 • ideal_gas, Fluid
PUBLISHED_GASES	mapping	The gases this library has read from a published page, keyed '<table>/<row>'. • Bies 5e Table C.2 prints thirty-seven gases and Hopkins Table A1 six, and both print air • each row holds the molar mass and the ratio of specific heats, which between them close every state the gas can be in • six cells of Table C.2 are not served: four molar masses that do not belong to the molecule their row names and two ratios outside what the quantity can be, each refusing with what the page prints and pointing at docs/ERRATA.md • saturated steam prints an interval, 1,25 to 1,32, so it has no single ratio and says so	fluids.PUBLISHED_GASES['hopkins-2007-table-a1/argon'].heat_capacity_ratio # 1.67 • Gas
gases_named	function	Every published row for a gas name, across the tables. • name: the gas as a table prints it, matched without case and ignoring a parenthesis, so 'air' finds 'Air (dry)' • returns both books' readings rather than choosing: carbon dioxide is 1,30 in one and 1,33 in the other	[g.table for g in fluids.gases_named('air')] # ['bies-2017-table-c2', 'hopkins-2007-table-a1'] • PUBLISHED_GASES
NonlinearityParameter	dataclass	One published value of the nonlinearity parameter B/A, with the conditions it was measured at. • b_over_a: B/A, dimensionless; the coefficient of nonlinearity is 1 + B/(2A) • temperature_c [°C]; static_pressure_pa [Pa] only on the rows of the one table that prints a pressure, year only on the one that prints a year • attributed_to['b_over_a']: the paper the value comes from, spelled out from the chapter's reference list; uncertainty['b_over_a']: the plus-or-minus where the page prints one	row = fluids.nonlinearity_named('mercury')[0] row.b_over_a, row.temperature_c # (7.8, 30) • PUBLISHED_NONLINEARITY, nonlinearity_named
PUBLISHED_NONLINEARITY	mapping	A hundred and sixty-four published values of B/A, keyed '<table>/<row>'. • Rossing (2014) Tables 8.1 to 8.4: pure water from 0 to 100 °C, water up to 50 MPa, organic liquids, liquid metals and liquefied gases • one row per measurement, so a substance measured by several papers is several rows that do not agree: at 30 °C water is 5.18 to 5.38 • not a model: nothing interpolates between temperatures or papers	fluids.PUBLISHED_NONLINEARITY['rossing-2014-table-8-2/water_30c_50mpa'].b_over_a # 5.82 • NonlinearityParameter, nonlinearity_named
nonlinearity_named	function	Every published B/A whose substance name contains the text. • name: matched without case against the name the page prints; 'water' answers with Tables 8.1 and 8.2 and the sea water of Table 8.4 • empty when nothing matches, which is not an error	len(fluids.nonlinearity_named('water')) # 81 • PUBLISHED_NONLINEARITY
characteristic_impedance	function	Characteristic impedance rho c [Pa·s/m]. • density ρ [kg/m³] • speed_of_sound c [m/s] The medium's own quantity, so it moved here from the impedance tube that used to publish it; Fluid exposes the same thing as a property	fluids.characteristic_impedance(1.186, 343.2) # 407.04
sea_water	function	Sea water at one point of the ocean. • temperature_c T [°C], required • salinity_psu S (Default: 35) • depth_m (Default: 0) • latitude_deg (Default: 45) • sound_speed_model: unesco (default), del_grosso, mackenzie, medwin	fluids.sea_water(temperature_c=10.0) • Fluid; rho = 1027.04 kg/m³, c = 1489.83 m/s. No heat-capacity ratio: no source here prints one
sea_water_density	function	Density of sea water (Ainslie 2010 Eq. 4.6, after Pierce 1989). • temperature_c T [°C] • salinity_psu S • absolute_pressure_pa P_w [Pa], absolute	fluids.sea_water_density(temperature_c=10.0, salinity_psu=35.0, absolute_pressure_pa=101989.16) # 1027.04 • ρ [kg/m³]
sea_water_sound_speed	function	Speed of sound in sea water, m/s. • temperature_c [°C] / salinity [ppt] / depth [m] • model: "unesco" (default) / "del_grosso" / "mackenzie" / "medwin" • latitude (Default: 45)	fluids.sea_water_sound_speed(25, 35, 1000)
depth_to_absolute_pressure_pa	function	Absolute static pressure at a depth (Ainslie 2010 Eq. 4.11). • depth_m z [m] • latitude_deg (Default: 45) Not zero at the surface: Eq. (4.11) puts 98 066,5 x 1,04 = 101 989,16 Pa there, which is Ainslie's own reference and 664 Pa above the 101 325 Pa standard atmosphere	fluids.depth_to_absolute_pressure_pa(depth_m=0.0) # 101989.16
depth_to_gauge_pressure_mpa	function	Gauge pressure at a depth (Leroy & Parthiot 1998). • depth_m Z [m] • latitude_deg (Default: 45) Zero at the surface; what the UNESCO and Del Grosso sound speeds want	fluids.depth_to_gauge_pressure_mpa(depth_m=1000.0) # 10.106
FluidWarning	warning class	State outside the domain its model states for itself. Annex F states 15 °C to 27 °C, 60 kPa to 110 kPa, 10 % to 90 % RH; outside it the result is an extrapolation, not a refusal	warnings.simplefilter("error", fluids.FluidWarning) Emitted by fluids.air
FluidAssumptionWarning	warning class	A condition the caller did not supply was assumed. Names the assumed values and what they are worth; passing every condition silences it	warnings.simplefilter("error", fluids.FluidAssumptionWarning) Emitted by fluids.air
FluidPropertyUnavailable	exception	A quantity the model does not determine. Raised instead of returning a number no source printed; names the model and what it does fix	f.density # on a model that fixes only a speed of sound
plate_longitudinal_speed / youngs_modulus_from_plate_speed	function / function	Quasi-longitudinal wave speed along a plate, and back (Hopkins Eq. 2.21). • youngs_modulus_pa E [Pa] or longitudinal_speed_m_s cL [m/s] • density_kg_m3 ρ, poisson_ratio ν between -1 and 1 • cL = sqrt(E / (ρ (1 - ν²))): the value the building-acoustics tables print	solids.plate_longitudinal_speed(2.0e11, density_kg_m3=7800.0, poisson_ratio=0.28) # 5274.6
beam_longitudinal_speed / youngs_modulus_from_beam_speed	function / function	Quasi-longitudinal wave speed along a beam, and back (Hopkins Eq. 2.20). • youngs_modulus_pa E [Pa] or longitudinal_speed_m_s cL [m/s] • density_kg_m3 ρ • cL = sqrt(E / ρ): a beam is unconstrained on its sides, so ν does not appear	solids.beam_longitudinal_speed(2.0e11, density_kg_m3=7800.0) # 5063.7
bulk_longitudinal_speed / youngs_modulus_from_bulk_speed	function / function	Pure longitudinal wave speed in an unbounded solid, and back (Norton & Karczub Eq. 1.225). • youngs_modulus_pa E [Pa] or longitudinal_speed_m_s cL' [m/s] • density_kg_m3 ρ, poisson_ratio ν between -1 and 0.5 • cL' = sqrt(E (1 - ν) / (ρ (1 + ν)(1 - 2ν))): the speed an elastic solver integrates, not the one a plate table prints	solids.bulk_longitudinal_speed(2.0e11, density_kg_m3=7800.0, poisson_ratio=0.28) # 5724.8
thickness_critical_frequency_product / DEFAULT_SPEED_OF_SOUND_M_S	function / float	The h f_c column of a materials table, from the plate wave speed. • plate_speed_m_s cL,p [m/s] • speed_of_sound c0 [m/s] (Default: 343) • h f_c = c0² sqrt(12) / (2 π cL,p), the exact constant: the rounded 1.8 of ISO 12354-1 misses Hopkins Table A2 by 0.8 %	solids.thickness_critical_frequency_product(5270.0) # 12.31 m Hz, Table A2 prints 12.3
SolidMaterial	dataclass	One row of a published materials table, with what the cell said. • Every quantity optional, because no two books print the same columns; .why_missing(field) says what the page had instead • Three speeds are three fields: bar_longitudinal_speed_m_s, plate_longitudinal_speed_m_s and bulk_longitudinal_speed_m_s, and longitudinal_speed_m_s holds the one a page prints without saying which, because at ν = 0,3 the plate speed is 4,8 % above the bar speed and the bulk speed 16 % above it • Four loss factors: flexural_loss_factor, longitudinal_loss_factor, in_situ_loss_factor, and loss_factor for a page that prints one and does not say which • basis, approximate, ranges, bounded_above, unquantified: what the cell was, when it was not a value; basis[field] is 'estimated' for a cell the page marks as an estimate • derived: field → how this library computed it; borrowed: field → the material a book took it from • attributed_to: per-cell credit; variant: which specimen, when a page prints several under one name • .basis_of(field), .is_approximate(field), .is_derived(field), .printed(field) to narrow or be refused	steel = solids.PUBLISHED_SOLIDS['hopkins-2007-table-a2/steel'] steel.youngs_modulus_pa # 1.996e11, derived • steel.attributed_to['flexural_loss_factor'] # 'Heckl, 1981'
PUBLISHED_SOLIDS	mapping	Two hundred and nineteen published solids from six books, keyed '<table>/<row>'. • Hopkins Table A2, twenty-five building materials (PDF pages 635-636) • Cremer 3e Table 4.3, thirteen metals over fifteen rows (PDF page 201), the one table that prints E, G, ν and both speeds together • Mechel Table 3, thirty-eight construction materials, plastics and metals (PDF pages 544-545), with no Poisson ratio, so its rows stop at the bar speed • Bies 5e Table C.1, one hundred and five metals, building materials, woods, plastics and honeycomb panels (PDF pages 747-750), whose loss factor column is two quantities and not a range • Long 2e Table 12.1, eighteen building materials credited to Beranek and Ver (PDF page 487), and Arau-Puchades Table 4.1, seventeen over eighteen rows (PDF page 129), neither of which says which longitudinal wave it prints • The key names the table because four of them print a steel and they are not the same steel • Only four of Hopkins' twenty-five Poisson ratios are measurements; the rest carry the book's 'Estimate' footnote and say so • Not a specification: block densities vary by manufacturer, which is why the pages print ranges	solids.PUBLISHED_SOLIDS['cremer-2005-table-4-3/gold'] • SolidMaterial, solids_named
solids_named	function	Every published row for a material, across the books. • Matches SolidMaterial.name without regard to case; empty when no page names it • Comparing two books has to be a deliberate act: a lookup returning one steel would be choosing between published values for you	solids.solids_named('Steel') # two rows, two tables • PUBLISHED_SOLIDS
DampingMaterial	dataclass	One commercial damping material, with the temperature and the frequency its loss factor peaks at. • max_loss_factor is the greatest loss factor the material reaches, not the loss factor at any temperature you happen to have • peak_temperature_at_10_hz_c, peak_temperature_at_100_hz_c, peak_temperature_at_1000_hz_c: where that peak sits at each frequency the table prints, because the band moves up in temperature as the material is worked faster • youngs_modulus_max_pa at the stiff end, youngs_modulus_min_pa at the soft end, youngs_modulus_transition_pa in the band where the loss factor peaks, which is the one that belongs beside it • loss_modulus_max_pa is the imaginary part, about max_loss_factor * youngs_modulus_transition_pa • .peak_temperature_c(frequency_hz) refuses a frequency the table does not print rather than reading the nearest column • converted: the page is in degrees Fahrenheit and psi, so every converted cell keeps the figure and the unit the page prints, ('3e5', 'psi')	ear = solids.damping_named('EAR C-1002')[0] ear.peak_temperature_c(100) # where its peak sits at 100 Hz • PUBLISHED_DAMPING, damping_named
PUBLISHED_DAMPING	mapping	Seventeen commercial damping materials, keyed '<table>/<row>'. • Vér & Beranek 2e TABLE 14.1 (PDF page 599), the only table in this library where a loss factor carries the temperature and the frequency that decide it • Every other loss factor here is a single number with neither, which is a property of a material only in the sense that a photograph is a property of a room • Not measurements: the page's own footnote says the values were read off published curves, and the text says to get damping data from the supplier • Three cells are corrupted in the printing, are registered in docs/ERRATA.md and are refused rather than guessed	solids.PUBLISHED_DAMPING['ver-beranek-2006-table-14-1/ear_c_1002'] • DampingMaterial, damping_named
damping_named	function	Every published damping material whose name contains the text. • Matches DampingMaterial.name without regard to case; empty when no page names it • A tuple and not one row, because a name can be printed by more than one table	solids.damping_named('3M') # five rows • PUBLISHED_DAMPING
DampingTreatment	dataclass	One damping treatment, rated by the decay rate of the chapter's standard steel panel. • decay_rate_db_s$ [\text{dB}/\text{s}] \text{at} 160 \text{Hz} \text{on} \text{a} 50 \times 50 \times 0{,}6 \text{cm} \text{plate}, $temperature_c [°C], adhered_area_percent [%], surface_density_kg_m2 [kg/m²] • a decay rate is the treatment on that plate, not a property of the material; at 160 Hz the plate's loss factor is the rate over 4 368, and it is not computed here • two rows print "No" for the bonded area, which why_missing hands back	row = solids.damping_treatments_named('metal')[0] row.decay_rate_db_s # 400 • PUBLISHED_DAMPING_TREATMENTS, damping_treatments_named
PUBLISHED_DAMPING_TREATMENTS	mapping	Eight asphalt felt damping treatments, keyed '<table>/<row>'. • Harris (1977) Table 14.2 (PDF page 496): one to four plies, plain, punched or notched, bonded or loose, under carpet or a metal sheet • most decay rates printed as a range, from 1 dB/s to 400	len(solids.PUBLISHED_DAMPING_TREATMENTS) # 8 • DampingTreatment, damping_treatments_named
damping_treatments_named	function	Every published damping treatment whose description contains the text. • name: matched without case against the Spanish description the page prints • empty when nothing matches	len(solids.damping_treatments_named('muescado')) # 3 • PUBLISHED_DAMPING_TREATMENTS
SolidNonlinearity	dataclass	One solid's ultrasonic nonlinearity parameter, as a page printed it. • nonlinearity_parameter: the page's β_avg = −(3 + K3/K2), averaged over the [100], [110] and [111] directions; dimensionless • comparable with a liquid's B/A + 2, not with its B/A • bonding: covalent, ionic, metallic, van der Waals or isotropic, in the page's words	solids.solid_nonlinearity_named('NaCl')[0].nonlinearity_parameter # 14.6 • PUBLISHED_SOLID_NONLINEARITY, solid_nonlinearity_named
PUBLISHED_SOLID_NONLINEARITY	mapping	Eight solids' nonlinearity parameters, keyed '<table>/<row>'. • Rossing (2014) Table 6.5 (PDF page 261) • five rows are crystal structures or bonding classes, three name a material; fused silica is the one negative value	len(solids.PUBLISHED_SOLID_NONLINEARITY) # 8 • SolidNonlinearity, solid_nonlinearity_named
solid_nonlinearity_named	function	Every published solid whose printed name contains the text. • name: matched without case; 'FCC' answers with both face-centred cubic rows • empty when nothing matches	len(solids.solid_nonlinearity_named('FCC')) # 2 • PUBLISHED_SOLID_NONLINEARITY
OrthotropicWood	dataclass	One wood's orthotropic plate constants, as a page printed them. • By Rossing's Eq. (15.86): plate_stiffness_d1_pa = Ex/12μ along the grain, plate_stiffness_d3_pa = Ey/12μ across it, plate_stiffness_d2_pa = νxy·Ey/6μ the Poisson coupling and plate_stiffness_d4_pa = Gxy/3 the twisting stiffness, in pascals • Not moduli: D1 is the along-grain modulus over 12μ, so none of them compares with SolidMaterial.youngs_modulus_pa, and the plate thickness enters separately • relative_scaling_factor is the fourth root of D1 over D3, as the page prints it: the stretch across the grain of the equivalent isotropic plate • .basis_of(field) answers 'estimated' for the cells the caption calls intelligent guesses rather than measurements	maple = solids.orthotropic_wood_named('maple')[0] maple.basis_of('plate_stiffness_d2_pa') # 'estimated' • PUBLISHED_ORTHOTROPIC_WOOD, orthotropic_wood_named
PUBLISHED_ORTHOTROPIC_WOOD	mapping	Two orthotropic woods, keyed '<table>/<row>'. • Rossing (2014) Table 15.5 (PDF page 632), after Woodhouse, whom every row credits • The only wood here that is not isotropic: spruce is thirteen times stiffer along the grain than across it (D1 over D3) • Maple's printed scaling factor does not follow from its own row, and the defect is registered in docs/ERRATA.md	solids.PUBLISHED_ORTHOTROPIC_WOOD['rossing-2014-table-15-5/spruce'] • OrthotropicWood, orthotropic_wood_named
orthotropic_wood_named	function	Every published orthotropic wood whose name contains the text. • Matches OrthotropicWood.name without regard to case; empty when no page names it	solids.orthotropic_wood_named('spruce') • PUBLISHED_ORTHOTROPIC_WOOD
PlateauMaterial	dataclass	One material's plateau-method constants, as a page printed them. • surface_density_per_mm_kg_m2 is the density divided by a thousand, kept in the unit the method uses it in • coincidence_height_db is the height of the plateau: the transmission loss the method draws as a horizontal line over the coincidence region • plateau_frequency_ratio is the width of the plateau, the page's B/A	al = solids.plateau_material_named('alumin')[0] al.surface_density_per_mm_kg_m2 * 3 # kg/m2 of a 3 mm sheet • PUBLISHED_PLATEAU_DATA, plateau_material_named
PUBLISHED_PLATEAU_DATA	mapping	Eight materials' plateau-method constants, keyed '<table>/<row>'. • Norton & Karczub 2e Table 3.1 (PDF page 261) • What the plateau method needs to sketch a single panel's transmission loss without solving the plate model, and what building.PLATEAU_MATERIALS and building.plateau_transmission_loss read	solids.PUBLISHED_PLATEAU_DATA['norton-karczub-2003-table-3-1/steel'] • PlateauMaterial, plateau_material_named
plateau_material_named	function	Every published plateau-method material whose name contains the text. • Matches PlateauMaterial.name without regard to case; empty when no page names it	solids.plateau_material_named('glass') • PUBLISHED_PLATEAU_DATA
ideal_gas / MOLAR_GAS_CONSTANT / IDEAL_GAS_VALIDITY	function / float / str	A gas from the two numbers a gas table prints. • temperature_c t [°C], required • heat_capacity_ratio γ (> 1: it is c_p/c_v and c_p − c_v is the gas constant), molar_mass_kg_mol M [kg/mol], required • static_pressure_pa p [Pa] (Default: None → 101 325, warns) • c = sqrt(γRT/M) and ρ = pM/(RT), so a gas that is not air or water is computed rather than typed • the density is light by 1 − Z, the compressibility factor's distance from unity: 0,7 % for CO₂ and 2 % for SF₆ • no viscosity, no thermal conductivity and no Prandtl number: nothing in the closure determines them	fluids.ideal_gas(temperature_c=20.0, heat_capacity_ratio=1.67, molar_mass_kg_mol=0.040, static_pressure_pa=101300.0) • Fluid; c = 319.0 m/s, rho = 1.663 kg/m³, which is Hopkins Table A1 for argon
DEFAULT_STATIC_PRESSURE_PA	float	One standard atmosphere [Pa]. 101325.0	DEFAULT_STATIC_PRESSURE_PA # 101325.0
DEFAULT_RELATIVE_HUMIDITY_PERCENT	float	Humidity assumed when none is supplied [%]. 50.0. There is no standard humidity: Annex F's own examples use 50 % and 65 %	DEFAULT_RELATIVE_HUMIDITY_PERCENT # 50.0
DEFAULT_CO2_MOLE_FRACTION	float	CO₂ mole fraction assumed when none is supplied. 0.0004, the value Clause F.2 recommends for laboratory conditions	DEFAULT_CO2_MOLE_FRACTION # 0.0004
ISO1683_REFERENCE_VALUES	mapping	The ISO 1683:2015 reference values every level is counted from, keyed [medium][quantity]. • 'gas', Table 1: sound_pressure 20 µPa, sound_exposure (20 µPa)² s, sound_power 1 pW, sound_energy 1 pJ, sound_intensity 1 pW/m² • 'liquid', Table 2: the same five re 1 µPa and 1 µPa² s, particle_displacement 1 pm, particle_velocity 1 nm/s, particle_acceleration 1 µm/s² and distance 1 m • 'solid', Table 3: displacement 1 pm, velocity 1 nm/s, acceleration 1 µm/s², force 1 µN, and velocity_alternative 50 nm/s from note b • every value in SI; the private references of the package read it, and scripts/check_reference_values.py keeps them doing so	metrology.ISO1683_REFERENCE_VALUES['gas']['sound_pressure'].value # 2e-05
ReferenceValue	dataclass	One row of the ISO 1683 table. • quantity, medium ('gas' / 'liquid' / 'solid'), value [in unit], unit (SI), printed (as the page prints it, prefix and all), table ('Table 1' to 'Table 3', or 'Table 3, note b')	row = metrology.ISO1683_REFERENCE_VALUES['solid']['force'] • row.value, row.unit # (1e-06, 'N')
verify_conformance	function	The conformance rule of IEC TC 29 (IEC 60942:2017 5.1.15, IEC 61672-1:2013 5.1.21). • deviation: measured deviation from the design goal, signed • uncertainty: actual expanded uncertainty, 95 % coverage • acceptance_limits: one number for ±, or (lower, upper), one end of which may be open ((70.0, math.inf) for a stop-band minimum) • max_uncertainty: maximum-permitted expanded uncertainty • unit: label for the figure (Default: 'dB') Conforms when the deviation is within the limits AND the uncertainty within the maximum, both inclusive; the uncertainty is not added to the deviation	v = metrology.verify_conformance(-1.2, uncertainty=0.3, acceptance_limits=(-1.2, 1.0), max_uncertainty=0.5) • v.passes # True (IEC 61672-1 Table C.1, example 7)
ConformanceVerification	dataclass	One deviation judged by the TC 29 rule. • deviation, uncertainty, lower_limit, upper_limit, max_uncertainty, unit • passes, deviation_within_limits, uncertainty_within_maximum • outcome 1 to 4 (E.2.2 / C.2.2) and reason, worded as Tables E.1 and C.1 print it • share_of_acceptance_limit, share_of_max_uncertainty • no truth value: bool(v) raises; .plot() draws it as Figure E.1	v.outcome, v.reason
verify_sound_calibrator	function	A sound calibrator against IEC 60942:2017. • calibrator_class: 'LS', 'LS/M', '1', '1/M' or '2' (Table 1) • measurements: a SoundCalibratorMeasurements • nominal_frequency_hz: selects the rows of Tables 2, 5, 7, A.1, A.3 and A.4; refused where the class has no limit (5.1.2) • environmental_test: 'full' (Tables 5 and 6) or 'abbreviated' (A.6.4.7) (Default: 'full') Every requirement given is judged by verify_conformance	res = metrology.verify_sound_calibrator('1', record, nominal_frequency_hz=1000.0) • SoundCalibratorVerification
SoundCalibratorMeasurements	dataclass	What a laboratory measured on a calibrator. • one pair per requirement, deviation and expanded uncertainty: level_deviation_db, fluctuation_db, frequency_deviation_percent, distortion_percent, supply_voltage_deviation_db, environmental_level_deviation_db, environmental_level_in_band_deviation_db, environmental_frequency_deviation_percent, field_immunity_deviation_db, each with its ..._uncertainty_... • static_pressure_correction_db: the manufacturer's correction for an LS/M or 1/M pistonphone, added to the level • each field one number or one per condition; .pairs(requirement)	metrology.SoundCalibratorMeasurements(level_deviation_db=0.12, level_uncertainty_db=0.10)
SoundCalibratorRequirement	dataclass	One IEC 60942 requirement, judged on each of its measurements. • name, clause, tables, verifications (one ConformanceVerification each) • passes, unit, acceptance_limits, max_uncertainty • no truth value; .plot() draws its measurements as Figure E.1	res.requirement('level').passes
SoundCalibratorVerification	dataclass	The IEC 60942:2017 verdict on one calibrator setting. • calibrator_class, nominal_frequency_hz, environmental_test, measurements • requirements in the order of CALIBRATOR_REQUIREMENTS; requirement(name), failed • passes: every requirement measured passes (False when nothing was measured) • no truth value; .plot() draws the share of each allowance used	res.passes, res.failed
CalibratorTableRow	dataclass	One row of an IEC 60942 table keyed by a range of nominal frequencies. • lower_hz, upper_hz, includes_lower, includes_upper (as the printed "> 63 to < 160" says) • class_ls, class_1, class_2, None where the table prints a dash • .contains(nominal_frequency_hz), .for_class(calibrator_class)	metrology.LEVEL_ACCEPTANCE_LIMITS_DB[2].class_1 # 0.25
CALIBRATOR_CLASSES	constant	IEC 60942:2017 Table 1 classes and designations: ('LS', 'LS/M', '1', '1/M', '2')	'1/M' in metrology.CALIBRATOR_CLASSES
CALIBRATOR_REQUIREMENTS	constant	The requirements verify_sound_calibrator grades: 'level', 'fluctuation', 'frequency', 'distortion', 'supply_voltage', 'environmental_level', 'environmental_level_in_band', 'environmental_frequency', 'field_immunity'	metrology.CALIBRATOR_REQUIREMENTS[0] # 'level'
LEVEL_ACCEPTANCE_LIMITS_DB	tuple	IEC 60942:2017 Table 2, sound pressure level [dB]: 0.10 / 0.25 / 0.40 (LS / 1 / 2) from 160 Hz to 1.25 kHz; class 1 alone elsewhere, 0.30 to 0.50 dB	metrology.LEVEL_ACCEPTANCE_LIMITS_DB[2].class_2 # 0.4
FLUCTUATION_ACCEPTANCE_LIMITS_DB	tuple	IEC 60942:2017 Table 2, short-term level fluctuation [dB]: 0.03 / 0.07 / 0.15 from 160 Hz to 1.25 kHz; class 1 0.20 dB to 63 Hz and 0.10 dB below 160 Hz	metrology.FLUCTUATION_ACCEPTANCE_LIMITS_DB[0].class_1 # 0.2
SUPPLY_VOLTAGE_ACCEPTANCE_LIMITS_DB	mapping	IEC 60942:2017 Table 3, effect of supply voltage [dB]: LS 0.02, 1 0.06, 2 0.16	metrology.SUPPLY_VOLTAGE_ACCEPTANCE_LIMITS_DB['1'] # 0.06
FREQUENCY_ACCEPTANCE_LIMITS_PERCENT	mapping	IEC 60942:2017 Table 4, frequency [% of the specified frequency]: LS 0.7, 1 0.7, 2 1.7	metrology.FREQUENCY_ACCEPTANCE_LIMITS_PERCENT['2'] # 1.7
ENVIRONMENTAL_LEVEL_ACCEPTANCE_LIMITS_DB	tuple	IEC 60942:2017 Table 5, level over the environmental range [dB]: 0.10 / 0.25 / 0.40 from 160 Hz to 1.25 kHz; class 1 0.25 to 0.60 dB elsewhere	metrology.ENVIRONMENTAL_LEVEL_ACCEPTANCE_LIMITS_DB[-1].class_1 # 0.6
ENVIRONMENTAL_FREQUENCY_ACCEPTANCE_LIMITS_PERCENT	mapping	IEC 60942:2017 Table 6, frequency over the environmental range [%]: LS 0.7, 1 0.7, 2 1.7	metrology.ENVIRONMENTAL_FREQUENCY_ACCEPTANCE_LIMITS_PERCENT['LS'] # 0.7
DISTORTION_ACCEPTANCE_LIMITS_PERCENT	tuple	IEC 60942:2017 Table 7, maximum total distortion + noise [%]: 2.0 / 2.5 / 3.0 from 160 Hz to 1.25 kHz; class 1 3.0 elsewhere	metrology.DISTORTION_ACCEPTANCE_LIMITS_PERCENT[1].class_ls # 2.0
LEVEL_MAX_UNCERTAINTY_DB	tuple	IEC 60942:2017 Table A.1, generated level [dB, 95 %]: 0.10 / 0.15 / 0.35 from 160 Hz to 1.25 kHz; class 1 0.20 to 0.50 dB elsewhere	metrology.LEVEL_MAX_UNCERTAINTY_DB[2].class_1 # 0.15
FLUCTUATION_MAX_UNCERTAINTY_DB	tuple	IEC 60942:2017 Table A.1, short-term fluctuation [dB, 95 %]: 0.02 / 0.03 / 0.05 from 160 Hz to 1.25 kHz	metrology.FLUCTUATION_MAX_UNCERTAINTY_DB[2].class_ls # 0.02
FREQUENCY_MAX_UNCERTAINTY_PERCENT	mapping	IEC 60942:2017 Table A.2, frequency [%, 95 %]: 0.2 for every class	metrology.FREQUENCY_MAX_UNCERTAINTY_PERCENT['1'] # 0.2
DISTORTION_MAX_UNCERTAINTY_PERCENT	tuple	IEC 60942:2017 Table A.3, total distortion + noise [%, 95 %]: 0.5 / 0.5 / 1.0 from 160 Hz to 1.25 kHz; class 1 1.0 elsewhere	metrology.DISTORTION_MAX_UNCERTAINTY_PERCENT[1].class_2 # 1.0
ENVIRONMENTAL_LEVEL_MAX_UNCERTAINTY_DB	tuple	IEC 60942:2017 Table A.4, level over the environmental range [dB, 95 %]: 0.10 / 0.15 / 0.20 from 160 Hz to 1.25 kHz; manufacturer's corrections included, Table A.1 excluded	metrology.ENVIRONMENTAL_LEVEL_MAX_UNCERTAINTY_DB[1].class_2 # 0.2
ENVIRONMENTAL_FREQUENCY_MAX_UNCERTAINTY_PERCENT	mapping	IEC 60942:2017 Table A.5, frequency over the environmental range [%, 95 %]: 0.2 for every class	metrology.ENVIRONMENTAL_FREQUENCY_MAX_UNCERTAINTY_PERCENT['2'] # 0.2
SUPPLY_VOLTAGE_MAX_UNCERTAINTY_DB	mapping	IEC 60942:2017 A.5.5.7 and A.5.5.8, supply-voltage difference [dB, 95 %]: LS 0.02, 1 and 2 0.04	metrology.SUPPLY_VOLTAGE_MAX_UNCERTAINTY_DB['2'] # 0.04
FIELD_IMMUNITY_ACCEPTANCE_LIMITS_DB	mapping	IEC 60942:2017 5.9.4.2, level change in a power- or radio-frequency field [dB]: LS 0.10, 1 0.25, 2 0.45	metrology.FIELD_IMMUNITY_ACCEPTANCE_LIMITS_DB['1'] # 0.25
FIELD_IMMUNITY_MAX_UNCERTAINTY_DB	mapping	IEC 60942:2017 A.7.4.8, that level change [dB, 95 %]: 0.05 for every class, the field measurement excluded	metrology.FIELD_IMMUNITY_MAX_UNCERTAINTY_DB['LS'] # 0.05
ABBREVIATED_LEVEL_REDUCTIONS_DB	mapping	IEC 60942:2017 A.6.4.7, reduction of the Table 5 limits in the abbreviated test [dB]: LS 0.05, 1 0.05, 2 0.10	metrology.ABBREVIATED_LEVEL_REDUCTIONS_DB['2'] # 0.1
ABBREVIATED_FREQUENCY_ACCEPTANCE_LIMITS_PERCENT	mapping	IEC 60942:2017 A.6.4.7, frequency limits of the abbreviated test [%]: LS 0.5, 1 0.5, 2 1.3	metrology.ABBREVIATED_FREQUENCY_ACCEPTANCE_LIMITS_PERCENT['2'] # 1.3
adjustment_factors	function	Adjustment factors K(φ) of one plane of readings (IEC 61183:1994 Formulas (6), (7), (A.1), (A.2)). • step_deg: the angular step Δφ [°], dividing 180° into at least two steps • planes: the number of planes n, Δα = 180°/n (Default: 2, the X-Y and X-Z planes of Annex A; 4 halves every factor, NOTE 2 of A.6; 1 doubles it, Formula (A.4)) • the 360/Δφ factors from 0°, read-only; with the poles in every plane's sum they add up to 1 • warns SphereDivisionWarning above the 3 % of A.1.6	metrology.adjustment_factors(10.0)[[0, 1, 9]].round(5) • [0.00095 0.00378 0.02179], Table A.1
largest_element_fraction	function	The largest element a set of incidence angles divides the sphere into (IEC 61183 A.1.6, A.1.7). • step_deg [°], planes (Default: 2) • the ring element nearest 90° or the polar cap, whichever is larger; one plane is judged on the two-plane division it stands for	metrology.largest_element_fraction(10.0) # 0.02179, the 2,2 % of A.1.7
SphereDivisionWarning	warning class	The angular step leaves an element larger than 3 % of the sphere. Emitted by adjustment_factors, directivity_factor and axisymmetric_directivity_factor (IEC 61183 A.1.6)	warnings.simplefilter('error', metrology.SphereDivisionWarning)
directivity_factor	function	Directivity factor from readings in two or more planes (IEC 61183 Formula (A.3)). • levels_db: L(φ) [dB], one row per plane, each at φ = 0, Δφ, …, 360° − Δφ: (2, 36) for Annex A • reference_level_db: L_rd [dB] (Default: None → the first plane's reading at 0°) • the readings at 0° and 180° enter every plane's sum, so an omnidirectional meter reads γ = 1; counted once, 10 lg γ would come out 0,008 dB high for that meter and more for a directional one	d = metrology.directivity_factor(levels) • DirectivityFactor; d.directivity_index_db
axisymmetric_directivity_factor	function	Directivity factor of a rotationally symmetric meter from one plane (IEC 61183 Formula (A.4)). • levels_db: L(φ, h) [dB], 1-D, at φ = 0, Δφ, … • reference_level_db [dB] (Default: None → the reading at 0°)	metrology.axisymmetric_directivity_factor(levels[0]) • DirectivityFactor
equal_area_directivity_factor	function	Directivity factor from 38 equal-area elements (IEC 61183 Formula (A.5)). • horizontal_levels_db: 20 readings [dB] at the directions of equal_area_incidence_angles • vertical_levels_db: 18 readings [dB], the same without the poles • reference_level_db [dB] (Default: None → the horizontal reading at 0°)	metrology.equal_area_directivity_factor(h_db, v_db) • DirectivityFactor, every weight 1/38
equal_area_incidence_angles	function	The 38 directions of the equal-area division (IEC 61183, note to A.1.8). • each direction halves its element's area in polar angle: φk = arccos[1 − (4k − 1)/19] • returns (horizontal, vertical) [°], 20 and 18, read-only • the note prints 77,9° and 282,1° where this gives 77,85° and 282,15° (errata)	h, v = metrology.equal_area_incidence_angles() h[4].round(1) # 77.8
DirectivityFactor	dataclass	The directivity factor of a meter at one frequency. • incidence_angles_deg, plane_angles_deg [°], levels_db [dB], weights: one entry per reading, read-only • reference_level_db [dB], gamma, largest_element_fraction, formula ('A.3' / 'A.4' / 'A.5'), each checked when built • .directivity_index_db = 10 lg γ [dB], .relative_levels_db [dB] • .plot(view=): 'response' (polar, one curve per plane) / 'weights'	d.gamma, d.directivity_index_db
random_incidence_sensitivity	function	Random-incidence sensitivity level, band by band (IEC 61183 Formulas (1), (A.6)). • frequencies_hz [Hz], increasing • free_field_level_db: G_F = L_rd − L_o [dB] • directivity_index_db: 10 lg γ [dB]; either may be one value for every band • G_RI = G_F − 10 lg γ	r = metrology.random_incidence_sensitivity([1000, 8000], 0.0, [0.05, 2.45]) • RandomIncidenceSensitivity
RandomIncidenceSensitivity	dataclass	G_F, 10 lg γ and G_RI at each frequency. • frequencies_hz [Hz], free_field_level_db, directivity_index_db, random_incidence_level_db [dB], read-only • .correction_db = G_RI − G_F [dB] • .plot(view=): 'levels' / 'correction'	r.correction_db # [-0.05 -2.45]
diffuse_field_sensitivity	function	Diffuse-field sensitivity level by comparison with a reference meter (IEC 61183 Formulas (8) to (11)). • frequencies_hz [Hz]; indicated_level_db L_D and reference_indicated_level_db L_D,ref [dB] • exactly one of reference_random_incidence_level_db (9), reference_free_field_level_db (10) or reference_pressure_level_db (11) [dB] • reference_directivity_index_db with (10), reference_diffuse_pressure_difference_db with (11) [dB] (Default: None → IEC61183_TABLE_B1 at each preferred frequency)	metrology.diffuse_field_sensitivity(f, l_d, l_ref, reference_pressure_level_db=0.0) • DiffuseFieldSensitivity
DiffuseFieldSensitivity	dataclass	The comparison of IEC 61183 clause 5, route by route. • frequencies_hz [Hz], indicated_level_db, reference_indicated_level_db, reference_sensitivity_level_db, reference_correction_db [dB], route ('random_incidence' / 'free_field' / 'pressure') • .level_difference_db ΔG_D, .reference_diffuse_field_level_db G_D,ref, .diffuse_field_level_db G_D [dB] • .plot(): the three against frequency	dd.diffuse_field_level_db
IEC61183_TABLE_B1	mapping	IEC 61183:1994 Table B.1, the type LS2aP/LS2F microphone, keyed by preferred frequency [Hz]. • 25 Hz to 20 kHz; the row printed "25 to 800" at each preferred frequency it covers • each value a ReferenceMicrophoneRow; rounded to 0,05 dB by the table	metrology.IEC61183_TABLE_B1[8000.0].directivity_index_db # 2.45
ReferenceMicrophoneRow	dataclass	One row of Table B.1. • directivity_index_db: 10 lg γ_ref [dB] • diffuse_pressure_difference_db: Δ_DP, diffuse-field less pressure sensitivity level [dB]	metrology.IEC61183_TABLE_B1[16000.0].diffuse_pressure_difference_db # 3.05
exact_frequencies	function	Exact base-ten frequencies between two limits (IEC 62585 Annex H, Formula (H.1)). • lowest_hz, highest_hz [Hz], inclusive • fraction: the step-width designator b (Default: 12, the one-twelfth octaves of Table H.1; 1 the exact octaves, 3 the thirds) • f_x = 1000 · 10^(3x/10b) [Hz], read-only	metrology.exact_frequencies(1000, 10000)[31] / 1000 # 5.956621
adjustment_value	function	The adjustment value at the calibration check frequency (IEC 62585 Annex A). • frequencies_hz [Hz], the check frequency among them; free_field_indicated_level_db [dB] before the adjustment; calibrator_reading_db: L4′ on the calibrator at the same sensitivity [dB] • keyword-only: calibrator_level_db L1 [dB]; incident_level_db [dB] (Default: None → L1); tolerance_db [dB], infinite where a band does not pull the fit (Default: None → equal weights); pressure_indicated_level_db [dB] (Default: None); check_frequency_hz (Default: 1000) • least-squares fit s = −Σ w d / Σ w, w = 1/t² (the module's reading of a text with no formula); ΔL = L1 − (L4′ + s)	a = metrology.adjustment_value(f, l_ff, 94.35, calibrator_level_db=94.0) • AdjustmentValue; a.adjustment_db
AdjustmentValue	dataclass	The free-field response before the adjustment and what the fit makes of it. • frequencies_hz [Hz], free_field_deviation_db [dB], calibrator_level_db, calibrator_reading_db [dB], check_frequency_hz [Hz], tolerance_db, pressure_deviation_db [dB] or None, read-only • derived, never stored: .weights, .sensitivity_adjustment_db s, .calibrator_indicated_level_db L4, .adjustment_db ΔL, .check_frequency_offset_db L2 − L1, .free_field_indicated_level_db L2, .pressure_indicated_level_db L3, .pressure_to_free_field_correction_db [dB] • .plot(): the deviation before and after, with the tolerances	a.sensitivity_adjustment_db, a.check_frequency_offset_db
sound_calibrator_correction	function	Free-field corrections for a multi-frequency sound calibrator (IEC 62585 Annex D, Formula (D.7)). • frequencies_hz [Hz]; slm_free_field_level_db, reference_free_field_level_db, slm_calibrator_level_db, reference_calibrator_level_db [dB]: L_ind1 to L_ind4, one value per frequency or one row per determination • keyword-only: reference_free_field_correction_db C_FF,RM from IEC/TS 61094-7 [dB]; free_field_level_difference_db, calibrator_level_difference_db [dB] (Default: 0); microphones: the microphone of each row, so the range is taken over the microphones (Default: None, each row its own)	c = metrology.sound_calibrator_correction(f, l1, l2, l3, l4, reference_free_field_correction_db=c_rm) • FreeFieldCorrection, clause 12
comparison_coupler_correction	function	Free-field corrections for a comparison coupler (IEC 62585 Annex E, Formula (E.6)). • as sound_calibrator_correction, with slm_coupler_level_db and reference_coupler_level_db [dB], named by what each reading is of (Formula (E.6) exchanges the two labels of Figure E.1, an erratum) • keyword-only: coupler_level_difference_db: the level at the meter less that at the reference [dB] (Default: 0); microphones (Default: None)	metrology.comparison_coupler_correction(f, l1, l2, l_slm, l_rm, reference_free_field_correction_db=c_rm) • FreeFieldCorrection, clause 13
electrostatic_actuator_correction	function	Free-field corrections normalised at the check frequency, for an electrostatic actuator (IEC 62585 Annex F, Formula (F.13)). • frequencies_hz [Hz]; slm_free_field_level_db, reference_free_field_level_db, slm_actuator_level_db [dB] • keyword-only: reference_sensitivity_level_db S_RM [dB re 1 V/Pa]; reference_channel_gain_db G_RC [dB] (Default: 0); actuator_level_db L_EA [dB] (Default: 0); free_field_level_difference_db [dB] (Default: 0); check_frequency_hz f0 (Default: 1000); microphones (Default: None) • zero at f0	metrology.electrostatic_actuator_correction(f, l1, l2, l3, reference_sensitivity_level_db=s_rm) • FreeFieldCorrection, clause 14
FreeFieldCorrection	dataclass	The corrections of every determination, their mean and their range. • frequencies_hz [Hz], corrections_db (determinations × frequencies) [dB], reference_correction_db [dB], source ('sound_calibrator' / 'comparison_coupler' / 'electrostatic_actuator'), check_frequency_hz (actuator only), microphones (one label per row, or None), read-only • .correction_db mean, .microphone_corrections_db the mean of each microphone, .range_db over the microphones, largest less smallest [dB], .determinations, .microphone_count, .formula ('D.7' / 'E.6' / 'F.13'), .clause (12 / 13 / 14) • .plot(): the mean, the range band and the reference's part	c.correction_db, c.range_db, c.clause
correction_uncertainty_budget	function	The uncertainty budget of a correction, 15 components of Table I.1 (IEC 62585 Annex I). • values_db: the value of each component as Table I.2 states it, keyed 'a1' to 'a15' [dB] • keyword-only: repeatability_dof of a15; frequency_hz [Hz]; correction_db [dB] (Default: 0); static_pressure_kpa [kPa]: below 97 adds the clause 6 component, outside 80 to 105 refused (Default: None); additional_components: further Quantity objects (Default: none); coverage (Default: 0.95) • on combine_uncertainty, sensitivities ±1, Welch-Satterthwaite dof, Student k	b = metrology.correction_uncertainty_budget(table_i2, repeatability_dof=2, frequency_hz=1000) • b.coverage_factor # 2.042 (Table I.2 prints 2,11, an erratum)
CorrectionUncertaintyBudget	dataclass	One budget at one frequency. • frequency_hz [Hz], descriptors, symbols, values_db [dB], divisors, dofs, uncertainty (the UncertaintyResult, refused unless it is the combination of the columns), coverage, read-only • .standard_uncertainties_db, .combined_uncertainty_db, .expanded_uncertainty_db [dB], .effective_dof, .coverage_factor, .correction_db • .plot(): one bar per component, Type A apart, with u_c, k and U	b.combined_uncertainty_db, b.effective_dof # 0.0590 29.98
IEC62585_TABLE_I1	mapping	IEC 62585:2012 Table I.1, the likely components of the uncertainty of a correction, keyed 'a1' to 'a15'. • each value an UncertaintyComponentRow: the symbol, the description, the distribution and the divisor (√3 rectangular, 2 for C_FF,RM, 1 for the repeatability)	metrology.IEC62585_TABLE_I1["a7"].divisor # 2.0
UncertaintyComponentRow	dataclass	One row of Table I.1. • symbol, description, distribution ('rectangular' / 'normal'), divisor	metrology.IEC62585_TABLE_I1["a15"].symbol # 'Repeatability'
maximum_expanded_uncertainty	function	The maximum permitted expanded uncertainty of a correction (IEC 62585 clauses 9 to 14). • frequencies_hz [Hz] • keyword-only: clause, 9 to 14 (10 from 63 Hz only) • 0,25 dB to 4 kHz and 0,35 dB above (9); 0,25, 0,35 to 8 kHz, 0,45 (10); 0,20, 0,30 (11); 0,25, 0,35 below 10 kHz, 0,50 from 10 kHz (12 to 14) [dB], read-only; a frequency within 2 % of a boundary reads as it	metrology.maximum_expanded_uncertainty([3981.07, 10000.0], clause=12) # [0.25 0.5]
verify_correction_uncertainty	function	Verify the expanded uncertainties of a set of corrections against the maxima of their clause (IEC 62585 clauses 5, 9 to 14). • frequencies_hz [Hz]; expanded_uncertainty_db [dB] • keyword-only: clause; correction_db [dB] and coverage_factor, for the clause 15 documentation (Default: None); correction_range_db [dB], clauses 12 to 14 only (Default: None) • a value equal to its maximum passes, and one that reaches it through floating-point arithmetic	v = metrology.verify_correction_uncertainty(f, u, clause=c.clause, correction_range_db=c.range_db) • CorrectionUncertaintyVerification
CorrectionUncertaintyVerification	dataclass	The verdict of one clause on a set of corrections. • clause, frequencies_hz [Hz], expanded_uncertainty_db, correction_db, coverage_factor, correction_range_db [dB], read-only • .maximum_uncertainty_db [dB], derived from the clause • .passes; bool() raises; .uncertainty_passes, .range_passes, .margin_db, .failing_frequencies_hz, .subject • .plot(): U and the range against the stepped maximum • .report(path, *, metadata=None): one-page PDF fiche of clause 15 n) and o)	v.passes v.report("iec62585.pdf")
combine_uncertainty	function	GUM law of propagation of uncertainty (ISO/IEC Guide 98-3 clause 5). • model: measurement function f(x1…xN) • quantities: input Quantity objects, in argument order • correlation: optional N×N matrix r_ij (Default: None → uncorrelated; non-identity with finite input dof → effective dof undefined, expanded() needs coverage_factor_override)	u = metrology.combine_uncertainty(lambda a, b: a*b, [metrology.Quantity(10.0, 0.1), metrology.Quantity(5.0, 0.2)]) • UncertaintyResult; uc = 2.062
monte_carlo	function	Monte Carlo propagation (Guide 98-3-1, Supplement 1). • model: vectorised f(x1…xN) • quantities: input Quantity objects • trials: M ≥ 2 (Default: 1000000; fixed, no adaptive 7.9) • coverage: interval probability (Default: 0.95) • seed: reproducibility (Default: None) • inputs sampled independently (no 6.4.8 multivariate path)	mc = metrology.monte_carlo(model, quantities, seed=1) • MonteCarloResult (mean, u, coverage interval)
rectangular	function	Type B quantity, rectangular PDF (GUM 4.3.7). • value, half_width a, name	rectangular(20.0, 0.5) • Quantity with u = a/√3 = 0.289
triangular	function	Type B quantity, triangular PDF (GUM 4.3.9). • value, half_width a, name	triangular(20.0, 0.5) • Quantity with u = a/√6
u_shaped	function	Type B quantity, U-shaped (arcsine) PDF. • value, half_width a, name	u_shaped(20.0, 0.5) • Quantity with u = a/√2
coverage_factor	function	Coverage factor k from the t-distribution (GUM clause 6, Annex G). • coverage: coverage probability in (0, 1) (Default: 0.95) • dof: effective degrees of freedom (Default: inf → the normal quantile)	metrology.coverage_factor() # 1.960 metrology.coverage_factor(0.95, dof=10) # 2.228
expanded_uncertainty	function	k and U = k·uc(y) of a GUM result (clause 6). • result: an UncertaintyResult • coverage (Default: 0.95) The same answer as result.expanded(coverage), as a function	k, U = metrology.expanded_uncertainty(u)
Quantity	dataclass	Input quantity of a measurement model (GUM clause 4). • value: estimate xi • uncertainty: u(xi) ≥ 0 • distribution: 'gaussian'/'rectangular'/'triangular'/'u-shaped' (Default: 'gaussian') • dof: degrees of freedom (Default: inf) • name: budget label	Quantity(94.0, 0.3, name="calibrator")
UncertaintyResult	dataclass	GUM propagation result. • value: y = f(x1…xN) • combined_uncertainty: uc(y) • sensitivities: ci = ∂f/∂xi • contributions: |ci|·u(xi) • effective_dof: Welch–Satterthwaite • names • .plot(): uncertainty budget	u.combined_uncertainty, u.contributions
MonteCarloResult	dataclass	Monte Carlo result. • value: sample mean • standard_uncertainty: sample std • interval: (low, high) coverage interval (§7.7) • coverage, trials	mc.value, mc.interval
UncertaintyWarning	warning class	GUM propagation advisory. Emitted when a propagation falls back outside its nominal assumptions	warnings.simplefilter('error', UncertaintyWarning)
trend_test	function	Nonparametric trend test on a sequence (Bendat & Piersol 4.5.2). • values: ≥ 10 observations or estimates • method: 'reverse_arrangements' (Default; Table A.6 acceptance regions, exact Mahonian p-value to N = 100) / 'runs' (about the median, exact Wald–Wolfowitz distribution; median ties discarded) • alpha: two-sided significance (Default: 0.05)	res = metrology.trend_test(values) • TrendTestResult; B&P Example 4.4: A = 86, accepted in (64, 125]
TrendTestResult	dataclass	Trend-test verdict. • statistic: reverse arrangements A or runs r • bounds: acceptance region (lower, upper], p_value, trend_free • mean, std: null moments (Eqs. 4.54–4.55) • values, method, n, alpha, median (runs-classification median) • .plot(): tested sequence with the verdict	res.statistic, res.bounds, res.trend_free
stationarity_test	function	Stationarity test on segment statistics (Bendat & Piersol 10.3.1.1). • x, fs • n_segments (Default: 20, as B&P Example 10.3), statistic: 'mean_square' (Default) / 'rms' / 'mean' / 'variance' • method, alpha as trend_test Trailing samples beyond equal segments are discarded	res = metrology.stationarity_test(x, fs) • StationarityTestResult
StationarityTestResult	dataclass	Stationarity verdict on a record. • segment_values, segment_times [s], segment_duration [s] • count, bounds, p_value, stationary, mean, std • statistic, method, alpha, n_segments, fs • .plot(): segment sequence with the verdict	res.stationary, res.segment_values
level_crossing_rate	function	Level-crossing rates vs the Rice expectation (Bendat & Piersol 5.5.1). • x, fs (mean removed first; oversample the band) • levels [signal units] (Default: 13 levels over ±3 RMS) • nperseg: Welch length for the spectral moments Gaussian: N0 = 2√(m2/m0), Na = N0·exp(−a²/2σ²)	res = metrology.level_crossing_rate(x, fs) • LevelCrossingResult
LevelCrossingResult	dataclass	Crossing rates (both slopes). • levels, rates [1/s], rice_rates [1/s] • zero_crossing_rate, zero_crossing_rate_rice, apparent_frequency [Hz] = N0/2 • sigma, duration [s], fs • .plot(): measured dots vs the Rice curve	res.zero_crossing_rate, res.apparent_frequency
peak_statistics	function	Peak rate, irregularity factor and peak heights (Bendat & Piersol 5.5.2–5.5.4). • x, fs (mean removed; band-limit before: m4 weights G(f) by f⁴) • nperseg: Welch length for the moments M = √(m4/m2), r = N0/2M ∈ (0, 1]	res = metrology.peak_statistics(x, fs) • PeakStatisticsResult
PeakStatisticsResult	dataclass	Peak (maxima) statistics. • peak_rate, peak_rate_rice [1/s], zero_crossing_rate_rice, irregularity_factor • peak_values: sorted standardized heights z = a/σ • .peak_exceedance(z) / .peak_density(z): Rice mixture (Eqs. 5.217/5.223; Rayleigh at r = 1, Gaussian at r → 0) • .plot(): empirical exceedance vs the Rice curves	res.irregularity_factor, res.peak_exceedance(4.0)
power_spectral_density	function	Welch PSD with statistical error analysis (Bendat & Piersol Ch. 8). • x, fs • window (Default: 'hann'), nperseg (Default: bin spacing of at most 4 Hz; the resolution bandwidth Be also depends on the taper ENBW), overlap (Default: 0.5) • scaling: 'density' [units²/Hz] / 'spectrum' [units²] • confidence: chi-square CI level (Default: 0.95)	res = signals.power_spectral_density(x, fs) • SpectralDensityResult (psd, CI, nd, ε)
cross_spectral_density	function	Welch cross-spectral density with magnitude/phase errors (Eqs. 9.33/9.52). • x, y, fs • window, nperseg, overlap, scaling as above	res = signals.cross_spectral_density(x, y, fs) • CrossSpectralDensityResult
coherent_output_spectrum	function	Gvv = γ²·Gyy, noise remainder and spectral SNR (Eqs. 9.55–9.56, 9.73). • x (input), y (output), fs • window, nperseg, overlap, scaling as above	res = signals.coherent_output_spectrum(x, y, fs) • CoherentOutputSpectrumResult
fractional_octave_smoothing	function	Constant-power 1/n-octave smoothing of a spectrum. • frequencies, values • fraction: the n of 1/n octave (Default: 3) • domain: 'power'/'amplitude'/'db' (Default: 'power')	s = signals.fractional_octave_smoothing(f, psd, 3.0) • smoothed array, same domain; flat spectra unchanged
miso_coherence	function	Multiple & partial coherence of a MISO system (Bendat & Piersol Ch. 7). • inputs: q input records, q ≥ 2 (sequence of 1-D arrays or a (q, n) array), output, fs • order: conditioning order (Default: 0..q−1) • window, nperseg, overlap, scaling as above	res = signals.miso_coherence([x1, x2], y, fs) • MISOCoherenceResult
MISOCoherenceResult	dataclass	Multiple/partial coherence of q correlated inputs and one output. • ordinary_coherence (q×F), multiple_coherence γ²y:x, partial_coherence (q×F, conditioned per order) • coherent_output_spectra Gvi (q×F, Σ Gvi + noise_psd = output_psd) • multiple_coherence_random_error (Eq. 9.98), coherent_output_random_error (Eq. 9.100) • .dominant_input(): per-band index of the strongest source • .plot(): coherent output spectra + coherences	res.multiple_coherence, res.dominant_input()
resolution_bias_error	function	First-order resolution bias at a resonance peak, εb ≈ −(Be/Br)²/3 (Eq. 8.141). • resolution_bandwidth Be [Hz] • half_power_bandwidth Br [Hz]	resolution_bias_error(1.0, 4.0) # -1/48
noise_signal	function	Colored Gaussian noise with an exact power-law PSD slope. • fs, seconds (Default: 1.0) • color: 'white'/'pink'/'red'/'blue'/'violet' (0/−3.01/−6.02/+3.01/+6.02 dB/oct) • rms (Default: 1.0) • seed: bit-reproducible per seed	pink = signals.noise_signal(48000, 10.0, color='pink', seed=7)
tone_burst	function	IEC 60268-1 tone burst (Clause A2): zero-crossing start, integral full periods. • fs, frequency, cycles • amplitude (Default: 1.0) • repetitions + repetition_rate [bursts/s]: repetitive train (Clause A2.2) • pre_silence, post_silence [s]	res = signals.tone_burst(48000, 5000, 25, repetition_rate=10, repetitions=4) • ToneBurstResult
resample_signal	function	Polyphase resampling with an explicit anti-alias spec (Kaiser FIR designed here). • x, fs, fs_new (rational ratio, e.g. 160/147) • stopband_attenuation_db (Default: 120) • transition_width: fraction of the smaller Nyquist (Default: 0.05) • max_denominator (Default: 1000)	res = signals.resample_signal(x, 44100, fs_new=48000) • ResampledSignalResult (signal + designed taps)
fractional_delay	function	Band-limited delay by a fractional number of samples (phase ramp). • x, delay [samples] (fractional, negative = advance) • mode: 'linear' (zero-padded, for transients; Default) / 'circular' (periodic records, machine-exact on bin-centered tones)	y = signals.fractional_delay(x, 0.37)
window_metrics	function	Figures of merit of any scipy window (Harris 1978). • window: name or (name, param) tuple • n: length (Default: 1024), DFT-even sampling as in Welch	m = signals.window_metrics('hann', 2048) • WindowMetricsResult
multitaper_psd	function	Thomson multitaper PSD from one whole record (Percival & Walden Ch. 7). • x, fs • time_half_bandwidth: NW (Default: 4), n_tapers: K (Default: 2·NW−1, capped at 2·NW) • adaptive: Thomson weights (Default: True) • scaling, confidence as above	res = signals.multitaper_psd(x, fs) • MultitaperSpectralDensityResult
ToneBurstResult	dataclass	Tone-burst record. • signal, envelope (rectangular gate), fs • burst_seconds, burst_samples, onset_sample • repetition_rate, period_samples, duty_cycle • .plot(): waveform + gating envelope	res.signal, res.duty_cycle
ResampledSignalResult	dataclass	Resampled record with its anti-alias design. • signal, fs, original_fs, up, down • filter_taps, n_taps, passband_edge_hz, stopband_edge_hz • stopband_attenuation_db, transition_width	res.signal, res.stopband_attenuation_db
WindowMetricsResult	dataclass	Window figures of merit. • enbw_bins, .enbw_hz(fs), coherent_gain • scalloping_loss_db, worst_case_processing_loss_db (positive losses) • highest_sidelobe_db (negative, re main lobe), mainlobe_width_3db_bins • .plot(): window + spectrum with metrics marked	m.enbw_bins # 1.5 for Hann
SpectralDensityResult	dataclass	Welch PSD with its statistical quality. • frequencies, psd, ci_lower/ci_upper, confidence • random_error = 1/√nd, n_segments, n_averages (effective nd), degrees_of_freedom • resolution_bandwidth Be [Hz] • .plot(): PSD in dB with the CI band	res.psd, res.n_averages, res.random_error
MultitaperSpectralDensityResult	dataclass	Multitaper PSD with per-frequency dof. • frequencies, psd, ci_lower/ci_upper, confidence • degrees_of_freedom ν(f), random_error = √(2/ν) • weights (K×F), eigenvalues λk, time_half_bandwidth, n_tapers, resolution_bandwidth 2W [Hz], adaptive • .plot(): density with the CI band	res.psd, res.degrees_of_freedom
CrossSpectralDensityResult	dataclass	Welch CSD with per-bin errors. • csd (complex), magnitude, phase (unwrapped), coherence • magnitude_random_error, phase_std [rad] • .plot(): magnitude, phase ±σ, coherence	res.magnitude, res.phase_std
CoherentOutputSpectrumResult	dataclass	SISO output decomposition. • output_psd Gyy, coherent_psd Gvv, noise_psd Gnn • snr, snr_db, random_error (Eq. 9.73), snr_random_error, coherence_bias • .plot(): spectra + SNR panel	res.coherent_psd, res.snr_db
spectrogram	function	Calibrated STFT power spectrogram (B&P 12.6.4.2): the Welch segmentation without the averaging. • x, fs • window, nperseg, overlap, scaling as above Column mean = Welch PSD bin by bin; a tone reads A²/2 ('spectrum') in every column	res = signals.spectrogram(x, fs, nperseg=1024, overlap=0.75) • SpectrogramResult
zoom_fft	function	Narrow-band spectrum on a fine grid via chirp-Z (B&P 11.5.4). • x, fs, f_min, f_max • n_points (Default: one per record resolution fs/N) • window (Default: 'hann') Tone on an analysis frequency reads amplitude A / power A²/2 exactly	res = signals.zoom_fft(x, fs, f_min=980.0, f_max=1016.0) • ZoomFFTResult
SpectrogramResult	dataclass	STFT power over the time-frequency plane. • times, frequencies, power (freq × time) • time_resolution T_B [s], resolution_bandwidth Be [Hz], random_error (= 1, unaveraged), n_segments, hop • .plot(): dB image (raster)	res.power[:, 0], res.time_resolution
ZoomFFTResult	dataclass	Zoom spectrum with amplitude calibration. • frequencies, spectrum (complex, |·| = tone amplitude), amplitude, power (= A²/2) • bin_spacing (grid) vs resolution_bandwidth Be (true resolution) • .plot(): power in dB over the band	res.frequencies[res.amplitude.argmax()]
correlation	function	Auto/cross-correlation via zero-padded FFT (B&P 11.4.2). • x, y (Default: None → autocorrelation), fs • normalization: 'biased' (1/N) / 'unbiased' (1/(N−|r|)) / 'coefficient' (ρ ∈ [−1, 1]) (Default: 'unbiased') • max_lag [s] (Default: full N−1)	res = signals.correlation(x, y, fs, normalization='coefficient') • CorrelationResult
correlation_random_error	function	ε[R̂xy(τ)] = [1+ρ⁻²]^½/√(2BT) (Eqs. 8.109/8.112). • coefficient ρxy(τ) • signal_bandwidth B [Hz], duration T [s] Valid for T ≥ 10·|τ|, BT ≥ 5	correlation_random_error(1/11, 100.0, 5.0) # 0.349 (Example 8.5)
time_delay	function	TDE: direct correlator, GCC (Knapp & Carter) or phase slope (Eq. 5.101b). • x, y, fs • method: 'gcc' (Default) / 'direct' / 'phase' • weighting: 'none'/'roth'/'scot'/'phat' (Default)/'ml' (Table I) • window, nperseg, overlap: shared Welch core ('gcc'/'phase') • max_delay [s], interpolation: 'parabolic' (Default)/'none', upsample (Default: 1) • signal_bandwidth [Hz]: enables the Eq. 8.129 delay uncertainty	res = signals.time_delay(x, y, fs, weighting='phat', upsample=16) • TimeDelayResult
impulse_response_delay	function	Sub-sample IR delay [s]: peak location refined by local upsampling + parabola. • ir, fs • reference: optional IR the delay is measured against (direct correlator) • interpolation (Default: 'parabolic'), upsample (Default: 8)	t0 = signals.impulse_response_delay(ir, fs) # ~1e-3-sample accuracy
align_impulse_responses	function	Align an IR onto a reference by its estimated sub-sample delay. • ir, reference, fs • interpolation, upsample as above Exact band-limited fractional shift (zero-padded phase ramp)	res = signals.align_impulse_responses(ir_b, ir_a, fs) • AlignedImpulseResponseResult
envelope	function	Hilbert envelope, instantaneous phase & frequency (B&P Ch. 13). • x, fs • decimation_factor (Default: 1) • antialias: zero-phase FIR decimation (Default: True; False = plain subsampling, the ECMA-internal convention)	res = signals.envelope(x, fs, decimation_factor=32) • EnvelopeResult
CorrelationResult	dataclass	Correlation estimate. • lags [s], values, coefficient (always carried), normalization, kind • .random_error(signal_bandwidth): per-lag ε (Eqs. 8.109/8.112) • .plot()	res.lags, res.values, res.random_error(2000.0)
TimeDelayResult	dataclass	Time-delay estimate. • delay [s], delay_samples (fractional), method, weighting • lags, correlation (the searched curve), peak_correlation ρ̂xy • delay_std (Eq. 8.129), delay_interval ±2σ (Eq. 8.130) with signal_bandwidth • .plot(): correlation with the delay marked	res.delay, res.delay_std
AlignedImpulseResponseResult	dataclass	Aligned IR pair. • aligned, reference, delay [s], delay_samples • .plot(): overlay	res.aligned, res.delay_samples
EnvelopeResult	dataclass	Envelope analysis. • times [s], envelope, phase [rad, unwrapped], instantaneous_frequency [Hz] • fs (output rate), signal, signal_fs, decimation_factor, antialias • .plot(): signal + envelope, instantaneous frequency	res.envelope, res.instantaneous_frequency
envelope_spectrum	function	Amplitude spectrum of the envelope: modulations as lines (B&P 13.3). • x, fs • kind: 'magnitude' (Default) / 'squared' (square-law detector, Fig. 13.11) • window (Default: 'hann', coherent-gain corrected), nfft • remove_dc (Default: True; mean kept in mean_level) AM tone A0, m: line A0·m at fm ('magnitude')	res = signals.envelope_spectrum(x, fs) • EnvelopeSpectrumResult
EnvelopeSpectrumResult	dataclass	Envelope spectrum. • frequencies [Hz], amplitude (line heights), mean_level, kind • times, envelope (detector output), window, remove_dc, fs, nfft • .plot(): envelope + spectrum	res.amplitude, res.mean_level
time_synchronous_average	function	Extract a periodic waveform of known period_s by time domain averaging (McFadden 1987 Eq. 5). • x, fs, period_s [s] (one revolution) • n_averages: whole periods to average (Default: as many as the record holds; choose N so N·q is integer to place a comb node on an interfering order q) • n_harmonics: comb-response span (Default: 8) Non-integer fs·period_s aligned by band-limited fractional delay	res = signals.time_synchronous_average(x, fs, period_s=1/32) • SynchronousAverageResult
SynchronousAverageResult	dataclass	Time synchronous average. • period_waveform, times [s], residual, residual_rms • n_averages, samples_per_period, period_s, fs, interpolated • noise_reduction_db = 10·log₁₀N, amplitude_snr_gain = √N • comb_frequencies [Hz], comb_response (|C(f)|) • .plot(): averaged waveform + comb filter	res.period_waveform, res.noise_reduction_db
comb_filter_response	function	Magnitude of the N-period_s synchronous-averaging comb filter (McFadden 1987 Eq. 8). • frequencies [Hz], period_s [s], n_averages |C(f)| = |sin(N·π·f·T)/(N·sin(π·f·T))|: unit teeth at harmonics k/T, nodes at j/(N·T)	c = signals.comb_filter_response(freqs, 1/32, 20)
regularized_inverse_filter	function	Kirkeby frequency-dependent regularized inversion (Kirkeby & Nelson 1999 Eq. (17)). • response: measured IR (array or ImpulseResponseResult; its fs rides along) • fs: Sample rate [Hz] • f_range: (f1, f2) equalized to unity (Required) • regularization_inside (Default: 1e-6) / regularization_outside (Default: 1.0), fractions of max|H|² • transition_octaves (Default: 1/3), n_fft, delay (Default: n_fft//2)	inv = signals.regularized_inverse_filter(ir, f_range=(100, 10000)) • InverseFilterResult
InverseFilterResult	dataclass	Regularized inverse filter. • inverse (time domain), spectrum (with modeling delay), response_spectrum, regularization = ε(f), frequencies, f_range, delay, fs • flatness_db: worst in-band deviation of |H·H_inv| from 0 dB • max_gain_db: out-of-band boost (≤ the 1/(2√ε) cap) • .apply(x): equalize, delay removed; .plot()	flat = inv.apply(recording)
cepstrum	function	Power/real/complex cepstrum (Havelock Chs. 27/87). • x, fs • kind: 'power' (Default, IDFT of ln|X|²) / 'real' (ln|X|) / 'complex' (invertible, phase unwrapped) • nfft: even, ≥ record (Default: record length) Echo a at t0: rahmonics (−1)^(n+1)·aⁿ/n at n·t0	res = signals.cepstrum(x, fs, kind='complex') • CepstrumResult
CepstrumResult	dataclass	Cepstrum. • quefrencies [s], cepstrum, kind, fs, nfft, linear_phase_samples • .invert(): homomorphic round trip (complex kind only) • .plot(): cepstrum vs quefrency	res.cepstrum, res.invert()
lifter	function	Lifter a log spectrum: envelope vs fine structure (Havelock Ch. 27). • x, fs, cutoff [s] • mode: 'lowpass' (Default, spectral envelope) / 'highpass' (ripple) • nfft Modes exactly complementary in dB	res = signals.lifter(x, fs, cutoff=0.004) • LifterResult
LifterResult	dataclass	Liftered log spectrum. • frequencies [Hz], spectrum_db, liftered_db • quefrencies, cepstrum (real), cutoff, mode, fs, nfft • .plot(): cepstrum + cutoff, spectrum overlay	res.liftered_db
echo_detection	function	Echo delay + reflection coefficient off the power cepstrum. • x, fs • min_quefrency [s] (Default: 16 samples), max_quefrency [s] (Default: nfft/2) • nfft Peak height = a exactly for one in-record echo	res = signals.echo_detection(ir, fs, min_quefrency=0.002) • EchoDetectionResult
EchoDetectionResult	dataclass	Detected echo. • delay [s], delay_samples, reflection_coefficient • quefrencies, cepstrum, search_range, fs, nfft • .plot(): cepstrum with the peak marked	res.delay, res.reflection_coefficient
minimum_phase	function	Minimum-phase response from |H| via the real cepstrum (B&P 13.1.4). • response: one-sided response or plain magnitude, rfft layout (DC–Nyquist) • oversample: trig-interpolated cepstral anti-aliasing factor (Default: 8) Input phase ignored; magnitude zeros floored at 1e-15 of the peak	h_min = signals.minimum_phase(np.abs(H)) • complex minimum-phase response, same bins
group_delay	function	Group delay τ_g = −(1/2π)·dφ/df of a sampled response. • response: one-sided complex, rfft layout • fs [Hz] Unwrapped phase, central differences; needs < π phase advance per bin	tau = signals.group_delay(H, fs) # seconds
excess_phase	function	Excess (all-pass) phase: unwrap(arg H) − φ_min. • response: one-sided complex, rfft layout • oversample (Default: 8) 0 for minimum phase, −2πf·t₀ for pure latency; the realizability limit of any stable causal inverse	phi_x = signals.excess_phase(H) # rad, 0 at DC
phase_decomposition	function	Minimum-phase / all-pass decomposition of a response. • response: one-sided complex, rfft layout (e.g. np.fft.rfft(ir)) • fs [Hz] • oversample (Default: 8)	res = signals.phase_decomposition(np.fft.rfft(ir), fs) • PhaseDecompositionResult
PhaseDecompositionResult	dataclass	Phase decomposition. • frequencies [Hz], magnitude, phase (measured, unwrapped, 0 at DC) • minimum_phase, excess_phase [rad], group_delay, excess_group_delay [s] • minimum_phase_response (complex), fs • .plot(): magnitude, phases, group delays	res.excess_phase, res.excess_group_delay
sound_power_anechoic	function	Precision sound power in an (hemi-)anechoic room (ISO 3745:2012). • levels_positions: (NM, NB) position levels [dB] • surface: 'sphere'/'hemisphere' • radius r [m] • background_levels + frequencies: for K1i • areas: partial areas Si (Eq. 13) (Default: equal-area Eq. 12) • temperature_c [°C] (Default: 23), static_pressure_kpa [kPa] (Default: 101.325) • air_absorption_coefficient: α(f) [dB/m] for C3 • sigma_omc [dB] (Default: 0), coverage_factor k (Default: 2.0)	res = emission.sound_power_anechoic(levels, 'hemisphere', radius=2.0, frequencies=f) • PrecisionSoundPowerResult
PrecisionSoundPowerResult	dataclass	ISO 3745 sound power result. • sound_power_level [dB], sound_power_level_a [dB] • surface_pressure_level, mean_pressure_level [dB] • background_correction: K1i (NM, NB) [dB] • c1, c2, c3: meteorological corrections [dB] • directivity_index DIi, non_uniformity_index VIr [dB] • surface_area [m²], surface • uncertainty, uncertainty_bands, coverage_factor • .plot()	res.sound_power_level, res.uncertainty
precision_positions	function	ISO 3745 microphone coordinates (Annex D/E). • surface: 'sphere' (Table D.1) / 'hemisphere' (Tables E.1/E.2) • radius r [m] • array: 'general'/'broadband' (Default: 'general') • count: 20 or 40 (Default: 40)	xyz = emission.precision_positions('hemisphere', radius=2.0) • (40, 3) coordinates [m]
precision_background_correction	function	Per-position background correction K1i (ISO 3745 Eq. 11). • source_levels / background_levels: (NM, NB) [dB] • frequencies [Hz]: per-band criterion (10 dB for 250–5000 Hz, 6 dB outside)	k1 = emission.precision_background_correction(src, bg, f) • K1i [dB]; clamped + SoundPowerWarning below the criterion
meteorological_corrections	function	Corrections C1, C2, C3 (ISO 3745 Eq. 14 block). • temperature_c θ [°C] (Default: 23), static_pressure_kpa ps [kPa] (Default: 101.325) • air_absorption_coefficient: α(f) [dB/m] for C3 (Default: None → C3 = 0) • radius r [m] (Default: 1.0)	met = emission.meteorological_corrections(temperature_c=23.0, static_pressure_kpa=101.325) • MeteorologicalCorrection; C1 = −0.128 dB, C2 = 0 at reference
MeteorologicalCorrection	dataclass	C1/C2/C3 corrections. • c1: reference-quantity correction [dB] • c2: radiation-impedance correction [dB] • c3: air-absorption correction [dB], scalar or per band	met.c1, met.c2, met.c3
precision_uncertainty	function	Expanded uncertainty U = k·√(σR0² + σomc²) (ISO 3745 Eq. 24/25). • sigma_r0: reproducibility (Tables 2/3) [dB] • sigma_omc [dB] (Default: 0.0) • coverage_factor k (Default: 2.0; 1.6 one-sided)	precision_uncertainty(0.5) # 1.0 • U [dB], scalar or per band
sound_power_intensity_precision	function	Sound power by intensity scanning, precision (ISO 9614-3:2002). • partial_intensity: (N, NB) signed In,i [W/m²] • areas: partial areas Si [m²] • frequencies [Hz]: for LWA • temperature_c [°C] (Default: 23), barometric_pressure_pa [Pa] (Default: 101325): for LW0 (Eq. 10)	res = emission.sound_power_intensity_precision(In, areas, frequencies=f) • PrecisionIntensityResult
PrecisionIntensityResult	dataclass	ISO 9614-3 scanning result. • partial_power: Pi = In,i·Si [W] • sound_power P, sound_power_level LW [dB] (NaN where P ≤ 0) • sound_power_level_normalized: LW0 [dB] • not_applicable_band: per-band bool • surface_area [m²], sound_power_level_a [dB] • .plot()	res.sound_power_level, res.not_applicable_band
precision_field_indicators	function	ISO 9614-3 Annex B field indicators. • segment_intensity: (N, NB) signed In,j [W/m²] • segment_pressure_levels: (N, NB) Lpj [dB] • time_window_intensity: (M, NB) for FT (Default: None)	fi = emission.precision_field_indicators(In, lp) • PrecisionFieldIndicators
PrecisionFieldIndicators	dataclass	Annex B indicators (per band). • ft: temporal variability (= F1) or None • f_pi_unsigned: F_pIn unsigned (= F2) • f_pi_signed: F_pIn signed (= F3), ≥ unsigned • fs: field non-uniformity FS (= F4)	fi.f_pi_signed, fi.fs
precision_qualification	function	The five ISO 9614-3 Annex C acceptance criteria. • indicators: PrecisionFieldIndicators • scan_intensity_level_1/_2: LIn per scan [dB] (criterion 1) • pressure_residual_index: δpI0 [dB] (criterion 2, K = 10) • field_nonuniformity_1/_2: FS per scan density (criterion 5) • frequencies [Hz] or repeatability_limit: Table 1 limit s	q = emission.precision_qualification(fi, pressure_residual_index=18.0) • PrecisionCriteria
PrecisionCriteria	dataclass	Annex C pass/fail per band. • criterion_1…criterion_5: bool arrays or None where not evaluable • qualified: conjunction of criteria 1–4 or None	q.qualified, q.criterion_2
plane_wave_frequency_range	function	Working plane-wave range (f_l, f_u) (ISO 10534-2 §4.2–4.5). • spacing s [m] • speed_of_sound c0 [m/s] • diameter_m d [m] (Default: None → spacing bound only) • shape: 'circular'/'rectangular'/'square' (Default: 'circular')	plane_wave_frequency_range(0.05, 343.2, diameter_m=0.1) # (343.2, 1990.6) • [Hz]
plane_wave_frequency_range_astm	function	Working plane-wave range (f_l, f_u) (ASTM E2611-19 6.2.3–6.2.5, 6.5.4). • spacing s [m] • speed_of_sound c [m/s] • diameter_m d [m] (Default: None → spacing bound only) • shape: 'circular'/'rectangular'/'square' (Default: 'circular')	plane_wave_frequency_range_astm(0.05, 343.2, diameter_m=0.1) # (68.6, 2011.2) • [Hz]; f_u s < 0.40 c, f_u d < 0.586 c (0.500 rectangular)
plot_impedance_tube_geometry	function	To-scale side view of the ISO 10534-2 tube. • spacing s, x1 [m] • diameter_m d [m], shape (Default: 'circular') • sample_thickness [m] (Default: 50 mm nominal) • language	plot_impedance_tube_geometry(spacing=0.05, x1=0.15, diameter_m=0.10) • Dimensioned drawing + plane-wave range; also ImpedanceTubeResult.plot_geometry()
plot_transmission_tube_geometry	function	To-scale side view of the ASTM E2611 tube. • l1, s1, l2, s2, thickness [m] • diameter_m d [m], shape (Default: 'circular') • language	plot_transmission_tube_geometry(l1=0.10, s1=0.05, l2=0.20, s2=0.05, thickness=0.05, diameter_m=0.10) • Four microphones + termination; also TransferMatrix.plot_geometry()
speed_of_sound_iso10534	function	Speed of sound (ISO 10534-2 Eq. 5). • temperature_c t [°C]	speed_of_sound_iso10534(temperature_c=19.85) # 343.2 • c0 = 343.2 √(T/293) [m/s], T = 273.15 + t
air_density_iso10534	function	Air density (ISO 10534-2 Eq. 7). • temperature_c t [°C] • atmospheric_pressure_kpa [kPa] (Default: 101.325)	air_density_iso10534(temperature_c=19.85) # 1.186 • ρ [kg/m³]
speed_of_sound_astm	function	Speed of sound (ASTM E2611-19 Eq. 4). • temperature_c T [°C]	speed_of_sound_astm(temperature_c=20.0) # 343.2 • 20.047 √(273.15 + T) [m/s]
air_density_astm	function	Air density (ASTM E2611-19 Eq. 5). • temperature_c T [°C] • atmospheric_pressure_kpa P [kPa] (Default: 101.325)	air_density_astm(temperature_c=20.0) # 1.202 • ρ [kg/m³]
hydraulic_diameter	function	Hydraulic diameter of a rectangular tube, 4A/P (ISO 10534-2 A.2.1.5). • width w [m] • height h [m]	hydraulic_diameter(0.08, 0.04) # 0.0533 • d_h = 2wh/(w + h) [m]; feed to tube_attenuation_constant
tube_attenuation_constant	function	Lower-bound tube attenuation k0″ (ISO 10534-2 Eq. A.18). • frequency f [Hz] • speed_of_sound c0 [m/s] • diameter_m d [m] (hydraulic for rectangular)	tube_attenuation_constant(1000.0, 343.2, 0.1) # 0.0179 • [Np/m]
tube_wavenumber	function	Complex wavenumber k0 = k0′ − j k0″ (ISO 10534-2 §2.6). • frequency f [Hz] • speed_of_sound c0 [m/s] • attenuation: k0″ [Np/m] (Default: None → lossless)	tube_wavenumber(1000.0, 343.2, attenuation=0.018) • 18.308 − 0.018j [1/m]
mic_calibration_factor	function	Microphone-mismatch calibration factor Hc (ISO 10534-2 Eq. 10). • h12_config1: H12 in the standard configuration • h12_config2: H12 with the microphones interchanged	hc = materials.mic_calibration_factor(h12_a, h12_b) • Hc = √(H12ᴵ/H12ᴵᴵ) (complex)
apply_mic_calibration	function	Apply the calibration factor (Eq. 13). • h12_uncorrected • calibration_factor: Hc	h12 = materials.apply_mic_calibration(h12_raw, hc) • H12 = H12,raw/Hc
reflection_factor	function	Complex reflection factor at the sample surface (ISO 10534-2 Eq. 17). • h12: corrected transfer function • spacing s [m] • x1: sample to the farther microphone [m] • wavenumber: complex k0	r = materials.reflection_factor(h12, spacing=0.05, x1=0.15, wavenumber=k0) • r = (H12 − HI)/(HR − H12)·e^(+2jk0x1)
absorption_from_reflection	function	Normal-incidence absorption coefficient (Eq. 18). • reflection: complex r	absorption_from_reflection(0.5) # 0.75 • α = 1 − |r|²
surface_impedance	function	Absolute surface impedance Z (Eq. 19). • reflection: complex r • characteristic_impedance: ρc0 [rayl]	surface_impedance(0.5, 407.0) # 1221 • Z = ρc0(1 + r)/(1 − r) [rayl]
normalized_surface_impedance	function	Normalised surface impedance Z/(ρc0) (Eq. 19). • reflection: complex r	normalized_surface_impedance(0.5) # 3.0
normalized_surface_admittance	function	Normalised surface admittance Gρc0 (Eq. 20). • reflection: complex r	normalized_surface_admittance(0.5) # 0.333 • (1 − r)/(1 + r)
two_microphone_impedance	function	Full two-microphone reduction (ISO 10534-2 Clause 7). • h12: corrected transfer function • frequency f [Hz] • spacing s [m], x1 [m] • speed_of_sound c0 [m/s], characteristic_impedance ρc0 [rayl] • attenuation: k0″ [Np/m] (Default: None) • diameter_m + shape: activate the plane-wave range check	res = materials.two_microphone_impedance(h12, frequency=f, spacing=0.05, x1=0.15, speed_of_sound=343.2, characteristic_impedance=407.0) • ImpedanceTubeResult
ImpedanceTubeResult	dataclass	Two-microphone result per frequency. • frequencies [Hz] • reflection: complex r (Eq. 17) • surface_impedance [rayl], normalized_impedance (Eq. 19) • absorption: α = 1 − |r|² (Eq. 18) • Retains spacing, x1, diameter_m, shape when supplied	res.absorption, res.normalized_impedance
ImpedanceTubeWarning	warning class	ISO 10534-2 advisory. Emitted by two_microphone_impedance for frequencies outside the plane-wave working range (Eqs. 1–4); the results are still returned	warnings.simplefilter('error', ImpedanceTubeWarning)
standing_wave_ratio_from_level	function	Standing-wave ratio from ΔL (ISO 10534-1 Eq. 15). • level_difference: Lmax − Lmin [dB]	standing_wave_ratio_from_level(20.0) # 10.0 • s = 10^(ΔL/20)
standing_wave_reflection_magnitude	function	Reflection magnitude from the SWR (Eq. 14). • swr: s ≥ 1	standing_wave_reflection_magnitude(10.0) # 0.818 • |r| = (s − 1)/(s + 1)
standing_wave_reflection	function	Complex reflection factor from the standing wave (Eqs. 17–23). • swr: s • first_min_distance: x_min1 [m] • wavelength: λ0 [m]	standing_wave_reflection(10.0, 0.05, 0.4) # -0.818j • phase φ = π(4x_min1/λ0 − 1)
standing_wave_absorption	function	Absorption from the SWR (Eqs. 9 + 14). • swr: s ≥ 1	standing_wave_absorption(10.0) # 0.331 • α = 4s/(s + 1)²
standing_wave_normalized_impedance	function	Normalised impedance from the standing wave (Eqs. 24–26). • swr, first_min_distance [m], wavelength [m]	standing_wave_normalized_impedance(10.0, 0.05, 0.4) • 0.198 − 0.98j
wave_decomposition	function	Decompose the field into (A, B, C, D) (ASTM E2611-19 Eqs. 17–20). • h1…h4: microphone transfer functions • l1, s1, l2, s2: geometry [m] • wavenumber k • diameter_m + shape: activate the plane-wave range check	A, B, C, D = materials.wave_decomposition(h1, h2, h3, h4, l1=0.2, s1=0.05, l2=0.2, s2=0.05, wavenumber=k) • Forward/backward amplitudes, both sides
face_quantities	function	Face pressures and velocities (Eq. 21). • a, b, c, d: wave amplitudes • wavenumber k, thickness d [m], characteristic_impedance ρc	p0, pd, u0, ud = materials.face_quantities(A, B, C, D, wavenumber=k, thickness=0.05, characteristic_impedance=407.0)
transfer_matrix_two_load	function	Two-load transfer matrix (ASTM E2611-19 Eqs. 17–22). • load_a, load_b: (H1, H2, H3, H4) per termination • l1, s1, l2, s2, thickness [m] • wavenumber, characteristic_impedance • frequencies (retained for .plot()), diameter_m + shape: range check	T = materials.transfer_matrix_two_load(load_a, load_b, l1=0.2, s1=0.05, l2=0.2, s2=0.05, thickness=0.05, wavenumber=k, characteristic_impedance=407.0) • TransferMatrix
transfer_matrix_one_load	function	One-load transfer matrix, symmetric specimen (Eqs. 23–24). • load: (H1, H2, H3, H4) • Same geometry/frequency/range-check parameters as transfer_matrix_two_load	T = materials.transfer_matrix_one_load(load, l1=0.2, s1=0.05, l2=0.2, s2=0.05, thickness=0.05, wavenumber=k, characteristic_impedance=407.0) • Requires reciprocity + symmetry
air_layer_transfer_matrix	function	Analytic loss-free air-layer matrix (validation reference). • wavenumber k • thickness d [m] • characteristic_impedance ρc [rayl]	T = materials.air_layer_transfer_matrix(k, 0.05, 407.0) • det(T) = 1, T11 = T22
TransferMatrix	dataclass	Acoustic transfer matrix [[T11, T12], [T21, T22]] (ASTM E2611-19 Eq. 16). • t11, t12, t21, t22: complex, scalar or per frequency • Solver-built matrices retain l1/s1/l2/s2, thickness, diameter_m, shape, frequencies, air_characteristic_impedance (so .plot() needs no arguments)	T.t11, T.t12
airflow_resistance	function	Airflow resistance R = Δp/qv (ISO 9053-1:2018 §3.1). • pressure_drop_pa Δp [Pa] • volume_flow_rate qv [m³/s]	airflow_resistance(2.0, 0.0005) # 4000.0 • [Pa·s/m³]
specific_airflow_resistance	function	Specific airflow resistance Rs (§3.2). • resistance R + area A, or pressure_drop_pa Δp + velocity u	specific_airflow_resistance(4000.0, 0.01) # 40.0 • Rs = R·A = Δp/u [Pa·s/m]
airflow_resistivity	function	Airflow resistivity σ = Rs/d (§3.3). • specific_resistance Rs [Pa·s/m] • thickness d [m]	airflow_resistivity(40.0, 0.05) # 800.0 • [Pa·s/m²]
linear_airflow_velocity	function	Linear airflow velocity u = qv/A (§3.4). • volume_flow_rate qv [m³/s] • area A [m²]	linear_airflow_velocity(5e-6, 0.01) # 0.0005 • [m/s]
static_airflow_resistance	function	Stepwise static-method determination (ISO 9053-1 §7.5). • velocities u [m/s], pressure_drops_pa Δp [Pa] (≥ 2 steps) • area A [m²] • thickness d [m] (Default: None → no σ) • evaluation_velocity [m/s] (Default: 0.0005)	res = materials.static_airflow_resistance([0.0005, 0.001, 0.002], [0.02, 0.041, 0.086], 0.01, 0.05) • StaticAirflowResult (Rs = 40.0, σ = 800)
StaticAirflowResult	dataclass	Static-method result at the evaluation velocity. • resistance R [Pa·s/m³], specific_resistance Rs [Pa·s/m] • resistivity σ [Pa·s/m²] or None • evaluation_velocity [m/s], pressure_drop_pa [Pa] • linear_coefficient a (zero-velocity Rs), quadratic_coefficient b	res.specific_resistance, res.resistivity
piston_volume_flow_rate	function	RMS piston volume flow qv = 2πf·h·AP (ISO 9053-2 §6.2). • frequency f [Hz] • stroke_amplitude h [m] • piston_area AP [m²]	piston_volume_flow_rate(2.0, 0.005, 0.01) # 0.000628 • [m³/s]
alternating_airflow_resistance	function	Alternating-method resistance (ISO 9053-2:2020 Formula 2). • level_specimen Lps / level_termination Lpt [dB] • piston_stroke_specimen hs / piston_stroke_termination ht [m] • frequency f [Hz] (1–4 Hz), cavity_volume V [m³] • static_pressure_pa [Pa] (Default: 101325) • kappa_prime κ′ (Default: 1.4; use effective_kappa for Annex A conformity) • background_level Lpb [dB] (Default: None)	r = materials.alternating_airflow_resistance(78.0, 60.0, piston_stroke_specimen=5e-3, piston_stroke_termination=5e-4, frequency=2.0, cavity_volume=7.854e-4) • R [Pa·s/m³]; AirflowResistanceWarning when criteria fail
ANNEX_A_AIR	Fluid	The air of the ISO 9053-2:2020 Annex A.3 reference state (23 °C, 101 325 Pa, 50 % RH). 345,866 52 m/s, 1,186 084 8 kg/m³, κ = 1,400 757 3, plus the conductivity and specific heat Clause F.6 gives • the default of thermal_boundary_layer_thickness and effective_kappa; pass a computed fluids.air() to work in the air of the laboratory instead	materials.ANNEX_A_AIR.speed_of_sound # 345.86652
thermal_boundary_layer_thickness	function	Thermal boundary-layer thickness b (ISO 9053-2 Formulas A.4/A.5). • frequency f [Hz] • Air properties (Default: Annex A.3 values)	thermal_boundary_layer_thickness(2.0) # 0.00183 • [m]
effective_kappa	function	Effective ratio of specific heats κ′ (Formula A.7). • cavity_surface S [m²], cavity_volume V [m³] • frequency f [Hz] • Air properties (Default: Annex A.3 values)	effective_kappa(0.0471, 7.854e-4, 2.0) # 1.37 • The Annex A.3 worked example
delany_bazley	function	Delany–Bazley one-parameter porous model (Mechel 2e G.11; Bies 5e Table D.1). • frequency f [Hz] • flow_resistivity σ [Pa·s/m²] • coefficients: preset name or (C1…C8) (Default: 'delany_bazley' rockwool/fibreglass) • fluid: Fluid (Default: PUBLISHED_AIR, 343.0 m/s and 1.205 kg/m³) • Warns outside 0.01 < X < 1 (X = ρf/σ)	med = materials.delany_bazley(f, 20000.0) • PorousMediumResult
miki	function	Miki (1990) positive-real revision of Delany–Bazley. • frequency f [Hz] • flow_resistivity σ [Pa·s/m²] • fluid: Fluid (Default: PUBLISHED_AIR) • Stays passive below the fit range; warns outside 0.01 < f/σ < 1	med = materials.miki(f, 20000.0) • PorousMediumResult
johnson_champoux_allard	function	JCA five-parameter rigid-frame model (Cox & D'Antonio 3e Eqs. 6.19–6.25). • frequency f [Hz], flow_resistivity σ [Pa·s/m²] • porosity φ, tortuosity T = α∞ • viscous_length Λ / thermal_length Λ′ [m] • fluid: Fluid carrying the air state the model needs, viscosity, Prandtl number, ratio of specific heats and static pressure (Default: PUBLISHED_AIR)	med = materials.johnson_champoux_allard(f, 20000.0, porosity=0.98, tortuosity=1.05, viscous_length=8.7e-5, thermal_length=1.7e-4) • PorousMediumResult
limp_frame	function	Limp-frame correction of any rigid-frame model (Allard & Atalla 2e Eqs. 11.53-11.55, Panneton 2007). • medium: a rigid-frame PorousMediumResult • frame_density ρ₁ [kg/m³] (bulk density of the frame) • porosity φ (Default: 1.0) • keeps K_e, corrects ρ_e; → ρ_t = ρ₁ + φρ₀ as ω → 0 and → rigid as ρ₁ → ∞	soft = materials.limp_frame(jca, frame_density=30.0, porosity=0.98) • PorousMediumResult, model 'materials.limp_frame(...)'
decoupling_frequency	function	Zwikker-Kosten decoupling frequency Fd (Allard & Atalla 2e Sect. 11.3.4 / Eq. 6.90). • flow_resistivity σ [Pa·s/m²] • porosity φ, frame_density ρ₁ [kg/m³] • Fd = σφ²/(2πρ₁): above it the frame stands still	gw = materials.PUBLISHED_POROUS['allard-2009-table-6-1/domisol_coffrage'] decoupling_frequency(gw.printed('flow_resistivity_pa_s_m2'), porosity=gw.printed('porosity'), frame_density=gw.printed('frame_density_kg_m3')) # 43.27 • [Hz]
limp_frame_applicable / LIMP_FRAME_CRITERIA	function / mapping	Published rule of thumb for treating a frame as limp (Allard & Atalla 2e pp. 253-254). • frame_bulk_modulus K_c [Pa] • criterion: 'doutres' (0.2, Default) / 'beranek' (0.05) • fluid_bulk_modulus K_f [Pa] (Default: 101325, isothermal air) → the book's "bulk modulus lower than 20 kPa"	limp_frame_applicable(20e3) # True • bool
biot_waves	function	The three Biot waves of a poroelastic layer (Allard & Atalla 2e Eqs. 6.67–6.84). • medium: the rigid-frame PorousMediumResult of the pores • porosity φ, tortuosity α∞ • frame_density ρ₁ [kg/m³], shear_modulus N [Pa] (complex, Im ≥ 0) • poisson_ratio ν (Default: 0)	w = materials.biot_waves(jca, porosity=0.94, tortuosity=1.06, frame_density=130.0, shear_modulus=2.2e6*(1+0.1j)) • BiotWavesResult
BiotWavesResult	dataclass	Two compressional waves and one shear wave. • compressional_wavenumber_1 / _2, shear_wavenumber δ [rad/m] • velocity_ratio_1 / _2 / _3 μ (fluid over frame) • elastic_p / _q / _r P, Q, R [Pa]; density_11 / _12 / _22 • .airborne_wavenumber, .frame_borne_wavenumber, .airborne_velocity_ratio, .frame_borne_velocity_ratio, .airborne_is_second • .plot(): the three wavenumbers vs frequency	w.airborne_wavenumber, w.plot()
biot_surface_impedance	function	Hard-backed Biot layer at normal incidence, closed form (Allard & Atalla 2e Eqs. 6.107–6.108). • waves: a BiotWavesResult • thickness l [m] • Glued backing; one layer; normal incidence only	zs = materials.biot_surface_impedance(w, 0.10) • complex [Pa·s/m]
poroelastic_transfer_matrix	`function$	**6 \times 6 \text{layer} \text{matrix} $[T p] = [Γ(−h)][Γ(0)]⁻¹(Allard & Atalla 2e Eq. 11.34, Table 11.1).**<br>•waves, thicknessh [m]<br>•transverse_wavenumber` kt = k sin θ [rad/m] (Default: 0) • Field vector [v1s, v3s, v3f, σ33s, σ13s, σ33f]	t = materials.poroelastic_transfer_matrix(w, 0.05) • (n, 6, 6) complex
frame_bulk_modulus	function	Bulk modulus Kb of the frame in vacuum (Allard & Atalla 2e Eq. 6.29). • shear_modulus N [Pa], poisson_ratio ν • Kb = 2N(ν+1)/(3(1−2ν)); feeds limp_frame_applicable	frame_bulk_modulus(2.2e6, 0.0) • complex [Pa]
frame_elastic_coefficient	function	Longitudinal coefficient Kc of the frame in vacuum (Allard & Atalla 2e Eq. 6.111). • shear_modulus N [Pa], poisson_ratio ν • Kc = 2(1−ν)N/(1−2ν) = Kb + 4N/3	frame_elastic_coefficient(2.2e6, 0.0) # 4.4e6 • complex [Pa]
frame_quarter_wave_resonance	function	λ/4 frame resonance of a glued layer (Allard & Atalla 2e Eq. 6.110). • thickness l [m] • shear_modulus N, poisson_ratio ν, frame_density ρ₁ • fr = (1/4l)√(Re(Kc)/ρ₁): the peak no equivalent fluid produces	frame_quarter_wave_resonance(0.10, shear_modulus=2.2e6*(1+0.1j), poisson_ratio=0.0, frame_density=130.0) # 459.9 • [Hz]
PorousMediumResult	dataclass	Equivalent-fluid characterisation. • characteristic_impedance Zc [Pa·s/m], wavenumber k [rad/m] (Im < 0) • effective_density, bulk_modulus (surface-normalised) • .normalized_impedance, .normalized_wavenumber • .plot(): normalised Zc/k components	med.characteristic_impedance, med.plot()
PorousMaterial	dataclass	One row of a published table of porous-material parameters. • Every quantity optional, because no two tables print the same columns; .why_missing(field) says what the page had instead, and .printed(field) narrows or refuses • flow_resistivity_pa_s_m2, porosity, tortuosity, viscous_length_um, thermal_length_um, thermal_permeability_m2, frame_density_kg_m3, thickness_mm • youngs_modulus_pa, shear_modulus_pa (real), poisson_ratio, structural_loss_factor: a page printing N(1 + jη) has printed shear_modulus_pa and structural_loss_factor • approximate, ranges, bounded_above, reported, unquantified: what the cell was, when it was not a value • derived: field → how this library computed it; attributed_to: per-cell credit; variant: which specimen, when a page prints several under one name • .medium(f) → PorousMediumResult; .frame_constants() → (N, ν) with N complex, refusing a row without its loss factor rather than reading it as 0 • Not a material database: a real specimen is characterised to ISO 9053 and ISO 10534-2	foam = materials.PUBLISHED_POROUS['allard-2009-table-13-1/foam'] med = foam.medium(f) • foam.source prints the page
PUBLISHED_POROUS	mapping	A hundred and ninety-four porous rows from twenty-six published tables, keyed '<table>/<row>'. • Two kinds of row: a specimen is one measured sample with every parameter a model needs, and a compiled row is one quantity over a class of material, almost always an interval • Allard & Atalla 2e, the specimen rows of nineteen tables over eight chapters, each one the input to a worked example of the book • Cox & D'Antonio 3e Tables 6.2, 6.3, 6.5, 6.8 and 6.9 and Mechel 2e Sect. G.1 and G.11, compiled from the literature; seven of the eight porosity ranges Cox credits to Mechel match Mechel's own page to the digit • The key names the table because the book prints one foam in four chapters and one glass wool in two, sometimes with a column the other page leaves out • Table 6.1 prints the glass wool's shear modulus in N/cm², Table 11.8 prints the same specimen's Young's modulus in pascals, and E/(2(1+ν)) reconciles them • Table 9.1 prints its lengths in millimetres and Table 13.1 in metres; all of them are stored in micrometres • Table 11.5 prints the word 'model' where a screen's tortuosity would go, and the row keeps the word rather than a number • The plates, septa and impervious screens these pages also print are not porous materials and are not here	materials.PUBLISHED_POROUS['allard-2009-table-11-2/soft_fibrous'] • PorousMaterial, porous_materials_named
porous_materials_named	function	Every published row for a specimen name, across the tables. • Matches PorousMaterial.name without regard to case; empty when no page names it • Five pages print a 'Foam' and they are five different foams, so a lookup returning one would be choosing between published parameter sets for you	materials.porous_materials_named('Foam') # five rows, five tables • PUBLISHED_POROUS
ResistiveSheet	dataclass	One thin resistive facing, with the flow resistance of one square metre of it. • specific_flow_resistance_pa_s_m is R_s = Δp/v, per unit area [Pa·s/m], the N·s/m³ of the page and the mks rayl of an older literature; it is not the per-metre flow_resistivity_pa_s_m2 of PorousMaterial, and the two differ by a thickness • normalized_flow_resistance is the same resistance over ρ₀c₀, as two of the tables print it; .reference_impedance_pa_s_m() divides one column by the other and gives back the impedance that table used • wires_per_cm, wire_diameter_um, thickness_mm, mass_per_area_kg_m2, nonlinearity_factor: what each table describes its facing by • surface_density_g_m2 is the same mass per unit area under the heading and in the unit the cloth table prints it in, g/m²; weave_construction is that table's weave, held as the text it is, '60 × 58', two counts over a length the page never states • table says which of the three printed tables the row came from; the maker is in attributed_to['row'] on the cloth table, which credits one per row, and in attributed_to['table'] on the sintered one, which credits one for all eleven	mesh = materials.resistive_sheet_named('80')[0] mesh.specific_flow_resistance_pa_s_m # 24.6 Pa·s/m • PUBLISHED_FLOW_RESISTANCE, resistive_sheet_named
PUBLISHED_FLOW_RESISTANCE	mapping	Twenty-nine thin resistive facings from three published tables, keyed '<table>/<row>'. • Vér & Beranek 2e TABLE 8.5 (PDF page 266), five woven wire mesh cloths; TABLE 8.6 (PDF page 267), thirteen glass fibre cloths; TABLE 8.7 (PDF page 267), eleven sintered porous metal sheets, one data file and one citation each • A resistance per unit area [Pa·s/m], for the facing over an absorber, and not the flow resistivity [Pa·s/m²] of PUBLISHED_POROUS • TABLE 8.7 prints its two resistance columns once per block and blank beneath; the value is carried down and each row that received it names the row it came from • The surface density of TABLE 8.6 is held as the page prints it, in g/m², and its note carries the oz/yd² beside it: the two printings disagree by about eleven per cent on all thirteen rows, one wrong factor, and the page does not say which column has it • Not a specification: the pages give no measurement method, no laboratory and no standard, and the values are the linear part of the resistance, for low particle velocity only	materials.PUBLISHED_FLOW_RESISTANCE['ver-beranek-2006-table-8-7/sintered_fm_122'] • ResistiveSheet, resistive_sheet_named
resistive_sheet_named	function	Every facing a page labels with this name, matched whole. • Matches ResistiveSheet.name without regard to case, and whole rather than in part, because these pages name their rows by mesh count and product code: a partial match would answer '12' with a mesh, two cloths and four sintered sheets • A tuple and not one row, because a name can be printed by more than one table	materials.resistive_sheet_named('FM 122') • PUBLISHED_FLOW_RESISTANCE
AbsorptionSpectrum	dataclass	One finish of a published absorption table, with its Sabine coefficient in each octave band. • absorption_coefficient_63 … absorption_coefficient_8000: one field per band, the band's centre frequency in hertz as the suffix, None where the page prints no value • .bands() the bands the row prints; .spectrum() → {band_hz: coefficient}; .absorption_coefficient(band_hz) narrows or refuses, naming the row and the band • mounting: the ASTM C423 mounting the page prints beside the row, 'A', 'E400', 'F' or empty; the same board on two mounts is two rows, because the airspace behind it changes what it does • thickness and density stay in name and variant as the page prints them; the hedges of every catalogue row apply band by band • a measurement of a specimen in a room, not a property of a material: representative, never a specification	row = materials.PUBLISHED_ABSORPTION['bies-2017-table-6-2/carpet_heavy_on_concrete'] row.spectrum() # {125: 0.02, 250: 0.06, ...} • PUBLISHED_ABSORPTION, AbsorptionAreaSpectrum
AbsorptionAreaSpectrum	dataclass	A row a table prints as an equivalent absorption area per person, per seat or per cubic metre of air rather than as a coefficient. • absorption_area_63_m2 … absorption_area_8000_m2, in square metres per unit of per, which is 'person' for an audience row • kept apart from the coefficients because it is added to a room's absorption, not multiplied by a surface, and the unit is in the field name so it cannot be mistaken for one • a row in sabins has been converted, and converted[field] keeps the page's figure and its unit, ('4.0', 'sabins')	materials.PUBLISHED_ABSORPTION_AREAS['bies-2017-table-6-2/audience_per_person_seated'].spectrum()[500] # 0.44 m² per person • PUBLISHED_ABSORPTION_AREAS
ABSORPTION_BANDS_HZ	constant	The octave bands an absorption table can print: 63 Hz to 8 kHz. • (63, 125, 250, 500, 1000, 2000, 4000, 8000); a table prints six or seven of them and the others stay empty on every row	materials.ABSORPTION_BANDS_HZ
PUBLISHED_ABSORPTION	mapping	Four hundred and fifty-five absorption coefficient rows from five published tables, keyed '<table>/<row>'. • Bies 5e Table 6.2, fifty-nine rows in eight groups, two of which are areas per person and live in PUBLISHED_ABSORPTION_AREAS • Long 2e Table 7.1, a hundred and two rows in eleven groups, with an ASTM C423 mounting on sixty-two of them and fifteen finishes printed on two mounts • Cox & D'Antonio 3e Appendix A, a hundred and sixty-one rows in twenty-two groups, compiled from twenty-nine sources and credited row by row in attributed_to; every cell of it is a number • Arau-Puchades (1999) Tabla 6.1, ninety-six of its ninety-nine numbered rows, names in Spanish as printed, two of them intervals in ranges; the three that are the air attenuation coefficient m in reciprocal metres are not served • Everest 4e Appendix, forty-one rows in three groups, each with the source the page prints beside it in a column of its own; two rows the page marks with a dash carry no credit • the book says the values are selected from the literature, that reverberation times from them are approximate only, and that manufacturer's data or a measurement is better • the transcription was made twice, from the rendered pages, by readers who never saw each other's work, and compared cell by cell before either was kept • of the ten finishes both books describe, five agree in every band and five differ in exactly one cell, which is why absorption_named returns every match rather than choosing one	materials.PUBLISHED_ABSORPTION['bies-2017-table-6-2/glass_heavy_plate'].absorption_coefficient(125) # 0.18 • AbsorptionSpectrum, absorption_named
PUBLISHED_ABSORPTION_AREAS	mapping	The four rows the same pages print as an absorption area rather than a coefficient, keyed '<table>/<row>'. • Bies 5e Table 6.2 prints an audience seated and standing as $S\bar{\alpha}$ in square metres, the quantity of its Equation (6.78) • Long 2e Table 7.1 prints a musician with his instrument, in bare figures its note reads as sabins, and the air itself at 50 % relative humidity, in sabins per 1000 cubic feet; both are converted to square metres and marked converted	materials.PUBLISHED_ABSORPTION_AREAS['bies-2017-table-6-2/audience_per_person_standing'].per # 'person' • AbsorptionAreaSpectrum
absorption_named	function	Every published coefficient row whose printed name contains a fragment. • name: a fragment, matched without case, because a finish is described rather than named and no two books describe one the same way • 'carpet' answers with every carpet of every table, and the caller reads the names to pick the one that is theirs	[r.name for r in materials.absorption_named('carpet')] # twenty-one carpets; 'moqueta' finds the Spanish ones • PUBLISHED_ABSORPTION
Carpet	dataclass	One carpet as a page printed it: its pile, what it is laid on, and its NRC. • noise_reduction_coefficient, the mean absorption at 250 to 2000 Hz; no band can be recovered from it • pile_weight_kg_m2 [kg/m²], pile_height_mm [mm], pile_surface and fibre in the page's words, mounting (bare concrete or a hair pad) • four pile weights whose two printed halves disagree are misprinted and serve nothing	row = materials.carpets_named('nylon')[0] row.noise_reduction_coefficient # 0.5 • PUBLISHED_CARPETS, carpets_named
PUBLISHED_CARPETS	mapping	Nineteen carpets, keyed '<table>/<row>'. • Harris 3e Table 30.2 (PDF page 704), eleven on bare concrete, NRC 0,25 to 0,55, and Table 30.3 (PDF pages 704 to 705), eight on a hair pad, NRC 0,40 to 0,70 • credited to the American Carpet and Rug Institute, the chapter's Reference 5	len(materials.PUBLISHED_CARPETS) # 19 • Carpet, carpets_named
carpets_named	function	Every published carpet whose construction, surface or fibre contains the text. • name: matched without case against the Spanish words the page prints, so 'nylon', 'lana' or 'de nudo' • empty when nothing matches	len(materials.carpets_named('nylon')) # 3 • PUBLISHED_CARPETS
porosity_from_bulk_density	function	Open porosity of a fibrous material from its two densities (Hopkins 2007 Eq. 1.160, printed p. 80). • bulk_density_kg_m3 ρ [kg/m³], fibre_density_kg_m3 ρ_fibre [kg/m³] • φ = 1 − ρ/ρ_fibre; holds for solid fibres with a binder of negligible mass • Refuses a bulk density at or above the fibre density	materials.porosity_from_bulk_density(60.0, fibre_density_kg_m3=2 600.0) # 0.977 • φ, between 0 and 1
airflow_resistivity_from_bulk_density / FibreResistivityFit	function / class	Airflow resistivity of a mineral wool from its bulk density (Hopkins 2007 Eq. 1.165, printed p. 81). • bulk_density_kg_m3 ρ [kg/m³] • fit: a published FibreResistivityFit carrying k1, k2, fibre_diameter_um and the bulk-density range it was fitted over • r = k₁ρ^(1+k₂)/d² with d in micrometres • Warns outside the fitted range: it is a regression through measured points, not a law	materials.airflow_resistivity_from_bulk_density(60.0, fit=materials.ROCK_WOOL_LONGITUDINAL_FIT) # 23 226 • σ [Pa·s/m²]
ROCK_WOOL_LATERAL_FIT / ROCK_WOOL_LONGITUDINAL_FIT / ROCK_WOOL_FIBRE_DENSITY_KG_M3	constant	The rock wool of Hopkins Fig. 1.49, as its page prints it (printed p. 81). • lateral k₁ = 353, k₂ = 0,63 over 31 to 155 kg/m³ • longitudinal k₁ = 780, k₂ = 0,59 over 38 to 162 kg/m³ • fibre diameter 4,75 µm, fibre density 2 600 kg/m³ • Mineral wool is anisotropic: the longitudinal resistivity is the higher of the two	materials.ROCK_WOOL_LATERAL_FIT.k1 # 353.0 • FibreResistivityFit, float
viscous_characteristic_length	function	Λ from the three parameters that are measured routinely (Allard & Atalla 2e Eq. 5.25, printed p. 80). • flow_resistivity_pa_s_m2 σ, porosity φ, tortuosity α∞ • fluid: Fluid (Default: PUBLISHED_AIR), for its viscosity • shape_factor c (Default: 1.0) • Λ = (8ηα∞/(σφ))^½/c; within a factor of two on 18 of the 23 specimens the book prints with all four columns, and nowhere near a carpet	materials.viscous_characteristic_length(40 000.0, porosity=0.94, tortuosity=1.06) # 6.4e-05 • Λ [m]
fibre_characteristic_lengths / FibreCharacteristicLengths	function / class	Both lengths of a fibrous layer from its geometry (Allard & Atalla 2e Eqs. 5.29 and 5.30, printed p. 81). • fibre_radius_m R [m], bulk_density_kg_m3 ρ, fibre_density_kg_m3 ρ_fibre [kg/m³] • Λ = Rρ_fibre/(2ρ), Λ′ = 2Λ, the fibre length per unit volume eliminated through its own definition • A different model from viscous_characteristic_length, and the lower estimate of the two throughout	materials.fibre_characteristic_lengths(2.375e-6, bulk_density_kg_m3=60.0, fibre_density_kg_m3=2 600.0) • FibreCharacteristicLengths: viscous_length_m, thermal_length_m
DELANY_BAZLEY_COEFFICIENTS	mapping	Bies 5e Table D.1 coefficient presets (C1…C8). 'delany_bazley' (rockwool/fibreglass), 'garai_pompoli' (polyester), 'dunn_davern' / 'wu' (foams)	DELANY_BAZLEY_COEFFICIENTS['garai_pompoli']
DELANY_BAZLEY_VALIDITY	tuple	Stated fit range in X = ρf/σ. (0.01, 1.0)	DELANY_BAZLEY_VALIDITY # (0.01, 1.0)
MIKI_VALIDITY	tuple	Miki fit range in f/σ. (0.01, 1.0)	MIKI_VALIDITY # (0.01, 1.0)
PUBLISHED_AIR	Fluid	The air the Johnson-Champoux-Allard model was published with. 343.0 m/s, 1.205 kg/m³, 1.84·10⁻⁵ Pa·s, Pr = 0.71, γ = 1.4, 101325 Pa • a phonometry.fluids.Fluid: pass a computed one to depart from the published constants • the fluid argument of the slow-sound and metadiffuser models defaults to it	PUBLISHED_AIR.density # 1.205
layered_absorber	function	Transfer-matrix multilayer prediction at one angle_rad (Cox & D'Antonio Eq. 2.29; Bies Eq. D.95; Mechel D.4). • frequency f [Hz] • layers: stack from the incidence side (AirLayer, PorousLayer, PoroelasticLayer, PerforatedPlateLayer, MicroperforatedPlateLayer, MembraneLayer) • angle_rad θ [rad] (Default: 0) • termination: 'rigid'/'free'/complex Z [Pa·s/m] (Default: 'rigid') • fluid: Fluid (Default: PUBLISHED_AIR)	res = materials.layered_absorber(f, [materials.PorousLayer(0.05, med)]) • LayeredAbsorberResult
plot_absorber_stack	function	To-scale cross-section of a layer stack. • layers: front layer first (or a single layer) • language	plot_absorber_stack(layers) • Dimensioned drawing, rigid backing at right; also LayeredAbsorberResult.plot_geometry() and layer.plot()
LayeredAbsorberResult	dataclass	Oblique-incidence prediction. • surface_impedance Zs, normalized_impedance • reflection R(θ), absorption α(θ) • transfer_matrix: (2, 2, n) chain matrix (det = 1) • .plot(): α(f) with |R| overlaid	res.absorption, res.surface_impedance
diffuse_field_absorption	function	Random-incidence (Paris) absorption (Mechel D.5 Eq. 9). • frequency, layers, termination as layered_absorber • angle_limit_rad [rad] (Default: π/2; 75°–87° truncations in use) • quadrature_points (Default: 64, Gauss–Legendre)	dif = materials.diffuse_field_absorption(f, layers) • DiffuseFieldAbsorptionResult
DiffuseFieldAbsorptionResult	dataclass	Paris-integral result. • absorption: α_dif(f) • angle_limit_rad [rad] • .plot()	dif.absorption
statistical_absorption	function	Closed-form Paris integral, locally reacting plane (Mechel D.5 Eq. 10). • normalized_impedance z = Zs/(ρc) (Re z > 0) • angle_limit_rad [rad] (Default: π/2) • Maximum over passive z is the published 0.951	statistical_absorption(1.567 + 0j) # 0.951
AirLayer	dataclass	Plain air gap. • thickness d [m] (0 allowed → transparent)	AirLayer(0.05)
PorousLayer	dataclass	Porous layer. • thickness d [m] • medium: PorousMediumResult on the solver frequency grid	PorousLayer(0.05, med)
PoroelasticLayer	dataclass	Porous layer with an elastic frame (full Biot theory). • thickness d [m] • medium: the rigid-frame PorousMediumResult on the solver grid • porosity φ, tortuosity α∞, frame_density ρ₁ [kg/m³] • shear_modulus N [Pa] (complex), poisson_ratio ν (Default: 0) • Switches layered_absorber to the global-matrix assembly; transfer_matrix is then NaN	PoroelasticLayer(0.05, med, 0.94, 1.06, 130.0, 2.2e6*(1+0.1j))
PerforatedPlateLayer	dataclass	Rigid perforated plate. • thickness t, hole_radius a [m] • open_area ε (0–1) • end_correction δ per end (Default: None → Fok/Nesterov of ε)	PerforatedPlateLayer(0.006, 0.0025, 0.05)
MicroperforatedPlateLayer	dataclass	Maa microperforated plate. • thickness t, hole_radius a [m] (submillimetre) • open_area ε • end_correction δ (Default: 0.85)	MicroperforatedPlateLayer(0.0002, 0.0001, 0.005)
MembraneLayer	dataclass	Limp impervious membrane. • surface_density m [kg/m²] • resistance r [Pa·s/m] (Default: 0)	MembraneLayer(5.0)
perforated_plate_impedance	function	Perforated-plate transfer impedance (Cox & D'Antonio Eqs. 7.6/7.12). • frequency, thickness, hole_radius, open_area, end_correction • fluid: Fluid (Default: PUBLISHED_AIR)	z = materials.perforated_plate_impedance(f, thickness=0.006, hole_radius=0.0025, open_area=0.05) • complex [Pa·s/m]
microperforated_plate_impedance	function	Maa's exact MPP impedance (Cox & D'Antonio Eqs. 7.33–7.35). • frequency, thickness, hole_radius, open_area • end_correction δ (Default: 0.85) • Bessel circular-capillary kernel	z = materials.microperforated_plate_impedance(f, thickness=0.0002, hole_radius=0.0001, open_area=0.005) • complex [Pa·s/m]
membrane_impedance	function	Membrane transfer impedance r + jωm (Cox Eq. 7.14; Bies Eq. D.96). • frequency, surface_density m [kg/m²] • resistance r (Default: 0)	z = materials.membrane_impedance(f, surface_density=5.0) • complex [Pa·s/m]
perforation_end_correction	function	End-correction factor δ(ε) = 0.85(1 − 1.47√ε + 0.47ε^1.5) (Cox Table 7.1). • open_area ε	perforation_end_correction(0.05) # 0.575 • per orifice end
helmholtz_resonance_frequency	function	Shallow-cavity perforate resonance (Cox Eq. 7.4). • cavity_depth d, plate_thickness t, hole_radius a [m] • open_area ε, end_correction δ • speed_of_sound	helmholtz_resonance_frequency(cavity_depth=0.025, plate_thickness=0.006, hole_radius=0.0025, open_area=0.05) • f0 = (c/2π)√(ε/(t′d)) [Hz]
membrane_resonance_frequency	function	Membrane mass-spring resonance (Cox Eqs. 7.9/7.10). • surface_density m [kg/m²], cavity_depth d [m] • isothermal (Default: False) • fluid: Fluid; the isothermal spring divides by the fluid's own ratio of specific heats (Default: PUBLISHED_AIR)	membrane_resonance_frequency(surface_density=5.0, cavity_depth=0.05) # ≈120 • ≈ 60/√(md) (50/√(md) isothermal) [Hz]
PorousAbsorberWarning	warning class	Porous-model advisory. Emitted when the Delany–Bazley / Miki regressions are evaluated outside their published fit range; values are still returned	warnings.simplefilter('error', PorousAbsorberWarning)
slit_helmholtz_absorber	function	Slit panel loaded with Helmholtz resonators (Jiménez et al. Appl. Sci. 2017). • frequency f [Hz], resonators: one/many HelmholtzResonator • slit_height h, lattice_step a, period_m d [m] • angle_rad θ [rad] (Default: 0) • end_correction, slit_radiation (Default: True) • visco-thermal slit + square-duct losses	res = materials.slit_helmholtz_absorber(f, hr, slit_height=1e-3, lattice_step=3e-2, period_m=5e-2) • SlitResonatorAbsorberResult
plot_slit_absorber_geometry	function	To-scale cross-section of one period_m of the slit panel. • resonators (one per lattice step) • slit_height h, lattice_step a, period_m d [m] • language	plot_slit_absorber_geometry([hr], slit_height=1e-3, lattice_step=0.03, period_m=0.05) • Also SlitResonatorAbsorberResult.plot_geometry()
plot_helmholtz_resonator_geometry	function	To-scale cross-section of a square-section Helmholtz resonator. • resonator: HelmholtzResonator • language	plot_helmholtz_resonator_geometry(hr) • Also HelmholtzResonator.plot()
SlitResonatorAbsorberResult	dataclass	Slow-sound panel prediction. • surface_impedance Z = T11/T21, normalized_impedance • reflection R(θ), absorption α = 1 − |R|² • effective_wavenumber, effective_impedance • transfer_matrix: (2, 2, n) • .plot(): α(f) with |R| overlaid	res.absorption, res.plot()
critical_coupling_design	function	Solve geometry for perfect absorption at a frequency (critical coupling, Eq. 9). • target_frequency f0 [Hz], base resonator • lattice_step a, period_m d [m], angle_rad θ • tunes cavity length + slit height so the reflection zero is real • warns if α does not reach ≈1	d = materials.critical_coupling_design(300.0, hr, lattice_step=3e-2, period_m=5e-2) • CriticalCouplingResult
CriticalCouplingResult	dataclass	Perfect-absorption design outcome. • resonator, slit_height: solved geometry • absorption (≈1), normalized_impedance (≈1) • converged, target_frequency, angle_rad	d.resonator, d.slit_height, d.absorption
HelmholtzResonator	dataclass	Square-cross-section Helmholtz resonator. • neck_length l_n, neck_side w_n [m] • cavity_length l_c, cavity_side w_c [m]	HelmholtzResonator(1e-3, 3e-3, 30e-3, 27e-3)
helmholtz_resonator_impedance	function	Resonator acoustic impedance Z_HR with visco-thermal losses (Jiménez et al. APL 2016 Eq. A23). • frequency, resonator • slit_height, lattice_step for neck→slit end correction • end_correction (Default: True)	z = materials.helmholtz_resonator_impedance(f, hr) • complex [Pa·s/m³]
slit_effective_properties	function	Narrow-slit visco-thermal ρ_s, κ_s (Stinson 1991; Eq. 6). • frequency, slit_height h [m] • fluid: Fluid (Default: PUBLISHED_AIR) • limit jωρ_s → 12η/h² as ω → 0	rho_s, kap_s = materials.slit_effective_properties(f, slit_height=1.2e-3)
rectangular_duct_properties	function	Square-duct visco-thermal ρ, κ (Stinson 1991; Eqs. 7–8). • frequency, side [m] • sum_terms (Default: 40) • limit jωρ → 28.454η/side² as ω → 0	rho, kap = materials.rectangular_duct_properties(f, side=3e-3)
SlowSoundAbsorberWarning	warning class	Slow-sound absorber advisory. Emitted when critical_coupling_design cannot reach perfect absorption within tolerance	warnings.simplefilter('error', SlowSoundAbsorberWarning)
AirflowResistanceWarning	warning class	ISO 9053 advisory. Emitted for a velocity above the 15 mm/s static limit, a piston frequency outside 1–4 Hz, or a failed Formula 3/4 validity criterion	warnings.simplefilter('error', AirflowResistanceWarning)
practical_absorption_coefficient	function	Practical coefficients αp (ISO 11654 §4.1). • third_octave_alpha_s: 15 one-third-octave αs, 200–5000 Hz (sequence or mapping keyed by band)	ap = materials.practical_absorption_coefficient(alpha_s) • 5 octave values (250–4000 Hz), 0.05 steps, capped at 1.00
weighted_absorption	function	Weighted absorption αw + class (ISO 11654 §4.2). • alpha_p: the 5 octave practical coefficients	w = materials.weighted_absorption([0.25, 0.7, 0.95, 1.0, 0.85]) • AbsorptionRatingResult (αw = 0.55, class D, 'MH')
weighted_absorption_from_third_octave	function	αw from 15 one-third-octave αs, retaining them for the fiche (ISO 11654 §4.1–4.2). • third_octave_alpha_s: 15 αs, 200–5000 Hz (sequence or mapping keyed by band)	w = materials.weighted_absorption_from_third_octave(alpha_s) • AbsorptionRatingResult carrying third_octave_alpha_s / third_octave_bands
absorption_class	function	Sound absorption class (Table B.1). • alpha_w: multiple of 0.05 in [0, 1]	absorption_class(0.7) # 'C' • 'A'–'E' or 'Not classified'
AbsorptionRatingResult	dataclass	αw rating result. • alpha_w: shifted curve read at 500 Hz • shape_indicator: 'L'/'M'/'H' concatenation or '' • absorption_class: 'A'–'E'/'Not classified' • shift, unfavourable_sum (≤ 0.10) • band_centers [Hz], measured, shifted_reference • .plot()	w.alpha_w, w.absorption_class
OCTAVE_BANDS	tuple	ISO 11654 octave rating bands [Hz]. (250, 500, 1000, 2000, 4000)	OCTAVE_BANDS # (250, ..., 4000)
THIRD_OCTAVE_BANDS	tuple	ISO 11654 one-third-octave input bands [Hz]. 200 Hz to 5000 Hz (15 bands)	THIRD_OCTAVE_BANDS[0] # 200
REFERENCE_CURVE	mapping	ISO 11654 Figure 1 reference curve (read-only). Keyed by octave band [Hz] → coefficient	REFERENCE_CURVE[250] # 0.8
check_ceiling_specimen / CeilingSpecimenCheck / TARGET_SPECIMEN_AREA_M2 / TEST_OBJECT_SIZE_M / TYPE_E_DEPTH_MM / MAX_DEFLECTION_MM	function / dataclass / constant	The test arrangement EN 16487 fixes, clause 4. • 10,80 m² of specimen, laid out in 0,6 m by 0,6 m objects, so a laboratory's own room does not change the answer • mounting type E hangs it 200 mm below the ceiling; the panels may sag no more than 5 mm • support_width_mm, support_height_mm, support_centre_distance_m: the support units of 4.1.1.2.3.6; relative_humidity_percent: one value per measurement, each held to the 50 % of 4.2.2 • check: deflection_ok, substructure_ok, fixture_ok, supports_ok, humidity_ok (None without a humidity) and satisfied over them; area_error_m2 and ce_marking_depth reported and not judged, since the area is a target and the 200 mm is the CE marking depth	materials.check_ceiling_specimen(area_m2=10.8, mounting="E", depth_mm=200.0)
mounting_type / MOUNTING_TYPES / SUBSTRUCTURE_LIMITS_MM / SUBSTRUCTURE_SPACING_M / SUPPORT_SECTION_MM / MIN_SUPPORT_SPACING_M / MIN_FIXTURE_DENSITY_KG_M2 / MIN_ROOM_EDGE_ANGLE_DEG	function / mapping / constant	How the specimen hangs, and on what. • the four mountings of EN ISO 354 Annex B this code uses: A against a hard surface, B glued with a 3 mm space, E suspended, J a discrete absorber • the exposed substructure at most 30 mm wide and 50 mm deep, on a 0,6 m grid, hung from 50 mm by 50 mm supports at least 1,2 m apart, the section and centre distance of which check_ceiling_specimen judges • a fixture counts as part of the specimen from 20 kg/m², and the specimen edges sit at least 10° off the room's own; the grid and the angle are targets and not judged	materials.mounting_type("E")
air_absorption_correction / AIR_CORRECTION_LIMIT / MIN_RELATIVE_HUMIDITY_PERCENT	function / constant	What the air in the room absorbs, 4.2.1. • 4V(m₂ − m₁)/S, as an absorption coefficient, from the attenuation with and without the specimen • over 0,05 the result is not reported: the air is doing too much of the absorbing to attribute it to the ceiling • the room is held at 50 % relative humidity or more, which is what keeps that term small at 4 kHz; check_ceiling_specimen(relative_humidity_percent=...) judges it for each measurement	materials.air_absorption_correction(volume_m3=200.0, specimen_area_m2=10.8, attenuation_with=m2, attenuation_empty=m1)
reproducibility_uncertainty / CEILING_UNCERTAINTY / WEIGHTED_UNCERTAINTY / EN16487_COVERAGE_FACTOR	function / mapping / constant	What two laboratories will differ by, Table 1. • the reproducibility standard deviation band by band: 0,23 at 125 Hz and 250 Hz, then 0,11, 0,10, 0,10 and 0,13 up to 4 kHz • 0,08 for the weighted single number α_w • expanded with k = 2,8, which is the factor the standard prints rather than the usual 2	materials.reproducibility_uncertainty() # one per octave band
SuspendedCeilingWarning	warning class	The test arrangement is outside a condition EN 16487 states. • a deflection over 5 mm, a substructure over 30 mm by 50 mm, a fixture under 20 kg/m², a type E plenum that is not 200 mm, an air correction over 0,05 • the specimen area is not one of them: 4.1.1.1.1 asks for "as close to 10,80 m² as possible", which is a target rather than a tolerance, so the check reports the difference and leaves the judgement to the laboratory	warnings.simplefilter('error', SuspendedCeilingWarning) Emitted by materials.absorbers.suspended_ceilings
speed_of_sound_iso17497	function	Speed of sound (ISO 17497-1 Eq. 2). • temperature_c t [°C]	speed_of_sound_iso17497(temperature_c=20.0) # 343.2 • 343.2 √((273.15 + t)/293.15) [m/s]
air_attenuation_coefficient	function	Energy attenuation m from ISO 9613-1 α (ISO 17497-1 Eq. 3). • pressure_attenuation_db_per_m: α [dB/m]	air_attenuation_coefficient(0.005) # 0.00115 • m ≈ α/4.343 [1/m]
random_incidence_absorption	function	Random-incidence absorption αs (ISO 17497-1 Eq. 1). • volume V [m³], area S [m²] • c1/T1: static base plate, no sample • c2/T2: with the test sample • m1/m2: air attenuation [1/m] (Default: 0)	a_s = materials.random_incidence_absorption(200.0, 10.8, c1=343.0, t1=2.5, c2=343.2, t2=1.8) # 0.463
specular_absorption_coefficient	function	Specular absorption αspec (Eq. 4). • volume, area • c3/T3: rotating base plate, no sample • c4/T4: sample on the rotating turntable • m3/m4 (Default: 0)	a_spec = materials.specular_absorption_coefficient(200.0, 10.8, c3=c3, t3=t3, c4=c4, t4=t4) • Includes the energy lost to scattering
scattering_coefficient	function	Random-incidence scattering coefficient s (Eq. 5). • alpha_spec, alpha_s • truncate_negative: clip s < 0 to 0 (Default: True); s > 1 is kept	scattering_coefficient(0.45, 0.30) # 0.214 • s = (αspec − αs)/(1 − αs)
scattering_coefficient_spectrum	function	Scattering spectrum s(f) (Eq. 5). • frequencies: one-third-octave centres [Hz] • specular_absorption, random_absorption: per band • truncate_negative (Default: True)	res = materials.scattering_coefficient_spectrum(f, a_spec, a_s) • ScatteringResult
ScatteringResult	dataclass	Scattering spectrum result. • frequencies [Hz] • scattering: s per band • random_incidence: αs, specular: αspec • .plot()	res.scattering
base_plate_scattering	function	Scattering of the base plate alone (Eq. 6). • volume, area • c1/T1: static, c3/T3: rotating • m1/m3 (Default: 0)	s_base = materials.base_plate_scattering(200.0, 10.8, c1=c1, t1=t1, c3=c3, t3=t3) • Quality metric vs Table 1
check_base_plate_scattering	function	Verify the base plate against Table 1 (Clause 6.2). • scattering: mapping by band [Hz] or 18 values ordered as BASE_PLATE_BANDS	check_base_plate_scattering(s_base) # () • Offending band centres; ScatteringDiffusionWarning if any
BASE_PLATE_BANDS	tuple	ISO 17497-1 base-plate check bands [Hz]. 100 Hz to 5000 Hz (18 one-third octaves)	BASE_PLATE_BANDS[0] # 100
BASE_PLATE_MAX_SCATTERING	mapping	Table 1 base-plate scattering limits (read-only). Keyed by band [Hz] → maximum s	BASE_PLATE_MAX_SCATTERING[500] # 0.05
reverberation_time_uncertainty	function	Standard uncertainty of a mean T (ISO 17497-1 Eq. A.1). • times: N ≥ 2 spatially-averaged measurements [s]	reverberation_time_uncertainty([2.31, 2.28, 2.35]) # 0.0203 • Standard error of the mean [s]
absorption_coefficient_uncertainty	function	Uncertainty of a Sabine coefficient (Eqs. A.3/A.4). • volume, area • speed_of_sound [m/s] • T_a/u_a, T_b/u_b: the two situations [s]	u_alpha = materials.absorption_coefficient_uncertainty(200.0, 10.8, speed_of_sound=343.2, t_a=2.5, u_a=0.02, t_b=1.8, u_b=0.02)
scattering_coefficient_uncertainty	function	Uncertainty of the scattering coefficient (Eq. A.5). • alpha_spec, alpha_s • u_alpha_spec, u_alpha_s	u = materials.scattering_coefficient_uncertainty(0.45, 0.30, 0.02, 0.02) • ScatteringUncertainty (U = 2u, 95 %)
ScatteringUncertainty	dataclass	Scattering uncertainty result. • u_scattering: combined standard u_s • expanded: U = 2u_s	u.u_scattering, u.expanded
PUBLISHED_SCATTERING	mapping	Forty-six measured surfaces from a published table, keyed '<table>/<row>'. • Cox & D'Antonio 3e Appendix D, nine groups from sinusoidal corrugation and battens through blocks, pyramids and grooves to hemispheres and vegetation • measured at full or model scale according to ISO 17497-1, and credited row by row to the seven papers the appendix lists; the book says nothing else about them • the only one of the book's four appendices whose numbers were measured rather than computed • how wide the method is: the same battens read 0.28 and 0.44 at 630 Hz in two papers, and one cell of the table is 1.17 • the transcription was made twice, from the rendered pages, by readers who never saw each other's work	row = materials.PUBLISHED_SCATTERING['cox-2017-appendix-d/pyramids_h_30_5_cm_l_b_h'] row.spectrum()[2000] # 0.58 • ScatteringCoefficientSpectrum, scattering_named
ScatteringCoefficientSpectrum	dataclass	One surface of a published table, with its scattering coefficient in each one-third octave band. • scattering_coefficient_100 … scattering_coefficient_5000, dimensionless, None where the page prints a dash or nothing • .bands(), .spectrum() → {band_hz: s}, .scattering_coefficient(band_hz) narrows or refuses, naming the row and the band • the geometry is in name as the page prints it and the family is in group, because 'h = w = 10 cm, L = 2h' means nothing on its own	row.scattering_coefficient(5000) # ValueError: the page prints a dash there • PUBLISHED_SCATTERING
SCATTERING_BANDS_HZ	constant	The one-third octave bands a published scattering table can print: 100 Hz to 5 kHz. • (100, 125, 160, ..., 4000, 5000), eighteen of them; twenty of Cox's rows stop at 4 kHz and ten print a dash there	materials.SCATTERING_BANDS_HZ[-1] # 5000
scattering_named	function	Every published surface whose description or group heading contains a fragment. • name: matched without case against both, because the useful word is usually in the heading • 'pyramid' answers with four rows, two of which the page describes identically	len(materials.scattering_named('vegetation')) # 6 • PUBLISHED_SCATTERING
PUBLISHED_DIFFUSION	mapping	Twenty-nine surfaces at three angles each, from a published table, keyed '<table>/<row>'. • Cox & D'Antonio 3e Appendix B, seven sections from periodicity and depth through triangles and semiellipses to Schroeder diffusers • normalized diffusion coefficients of ISO 17497-2, computed with a 2D boundary element model and not measured, which is the difference between this table and PUBLISHED_SCATTERING • the page prints three lines per surface, headed 0, 57 and Random, so a surface is three rows and variant says which • what an array does that one device does not: one semicylinder is 0.77 at 1 kHz at random incidence and twelve of it are 0.22 • the transcription was made twice, from the rendered pages, by readers who never saw each other's work	row = materials.PUBLISHED_DIFFUSION['cox-2017-appendix-b/2_30_cm_deep_semicylinders_random'] row.spectrum()[5000] # 0.65 • NormalizedDiffusionSpectrum, diffusion_named
NormalizedDiffusionSpectrum	dataclass	One surface at one angle of incidence, with its coefficient in each one-third octave band. • diffusion_coefficient_100 … diffusion_coefficient_5000, dimensionless; this appendix fills every cell • angle_of_incidence_deg: 0 or 57, and None on a random incidence row, which is a mean over ten angles and is none of them • .bands(), .spectrum() → {band_hz: d}, .diffusion_coefficient(band_hz) narrows or refuses • group carries the numbered section heading, which is where the geometry a row is short for is printed	row.why_missing('angle_of_incidence_deg') # the page prints "Random" there • PUBLISHED_DIFFUSION
DIFFUSION_BANDS_HZ	constant	The one-third octave bands a published diffusion coefficient table can print: 100 Hz to 5 kHz. • (100, 125, 160, ..., 4000, 5000), the same eighteen the scattering tables use, and Cox's appendix fills all of them on all eighty-seven rows	materials.DIFFUSION_BANDS_HZ[0] # 100
diffusion_named	function	Every published surface whose description or section heading contains a fragment. • name: matched without case against both, because the geometry is in the heading • a surface answers with its three angles, so '12 periods, 7.32 m wide' gives three rows	[r.variant for r in materials.diffusion_named('12 periods, 7.32 m wide')] # ['normal', '57 degrees', 'random'] • PUBLISHED_DIFFUSION
PUBLISHED_PREDICTED_SCATTERING	mapping	A hundred and nineteen rows of computed scattering, keyed '<table>/<row>'. • Cox & D'Antonio 3e Tables C.1, C.2 and C.3: two three-dimensional predictions at normal and random incidence over 250 Hz to 4 kHz, and one two-dimensional one over 100 Hz to 5 kHz at 0, 56.9 and random incidence • kept apart from PUBLISHED_SCATTERING, which is measured, so that a solver's number and a reverberation room's cannot be mixed unnoticed; no key is shared and the classes differ • the two three-dimensional tables are credited to Lee and Sakuma (2015), which the appendix prints as a source line under each • the book's own warnings about the coefficient, which reads absorption as scattering and redirection as dispersion, are in the about of each table	row = materials.PUBLISHED_PREDICTED_SCATTERING['cox-2017-table-c1/sinusoidal_cross_section_h_4_cm_l_20_cm'] row.model # 'three-dimensional boundary element prediction' • PredictedScatteringSpectrum, predicted_scattering_named
PredictedScatteringSpectrum	dataclass	One predicted surface at one angle, with its coefficient in each one-third octave band. • scattering_coefficient_100 … scattering_coefficient_5000, dimensionless; the three-dimensional tables leave the four lowest empty and say why • angle_of_incidence_deg: 0 or 56.9, and None where the page prints a word, "Random" or "All/any", which why_missing tells apart • model: the solver behind the row, which is what separates these from the measured ones • .bands(), .spectrum(), .scattering_coefficient(band_hz)	row.scattering_coefficient(100) # ValueError: the page has nothing there • PUBLISHED_PREDICTED_SCATTERING
predicted_scattering_named	function	Every predicted surface whose description or heading contains a fragment. • name: matched without case against both, because the topology is in the heading • 'batten' answers with sixteen rows across two tables	len(materials.predicted_scattering_named('sinusoidal cross-section')) # 12 • PUBLISHED_PREDICTED_SCATTERING
directional_diffusion_coefficient	function	Directional diffusion coefficient d_θ (ISO 17497-2 Formulas 5/6). • levels: n ≥ 2 reflected SPL [dB] (−inf = zero energy) • area_weights: Ni (Formula 8) (Default: None → equal-area Formula 5)	directional_diffusion_coefficient([-10., -12., -15., -11., -13.]) # 0.854
directional_diffusion	function	Polar response + its coefficient. • angles_deg [°], levels [dB] • weights: Ni (Default: None)	res = materials.directional_diffusion(angles_deg, levels) • DiffusionResult
plot_goniometer_geometry	function	Free-field diffusion goniometer in plan, to scale. • source_distance (Default: 10 m), receiver_radius (Default: 5 m) • angular_step (Default: 5°, 37 microphones) • sample_width [m] (Default: 0.6) • language	plot_goniometer_geometry()
DiffusionResult	dataclass	Polar diffusion result. • angles_deg [°], levels [dB] • coefficient: d_θ (autocorrelation) • .plot(), .report()	res.coefficient
diffusion_spectrum	function	Diffusion spectrum d(f) (ISO 17497-2 Clause 8.5). • frequencies: one-third-octave centres [Hz] • diffusion: d per band (directional, or random-incidence via Clause 8.4) • normalized: d_n per band (Default: None)	res = materials.diffusion_spectrum(f, d, normalized=d_n) • DiffusionSpectrum
DiffusionSpectrum	dataclass	Diffusion spectrum result. • frequencies [Hz] • diffusion: d per band • normalized: d_n per band or None • .plot(), .report()	res.diffusion
normalized_diffusion_coefficient	function	Normalised coefficient d_θ,n (Formula 7). • d_theta: test surface • d_theta_reference: flat reference	normalized_diffusion_coefficient(0.6, 0.2) # 0.5 • (d − d_r)/(1 − d_r)
area_factors	function	Per-receiver area weights Ni (Clause 8.3 Formula 8). • elevations: θ [°], 0–90 • delta_theta [°] • delta_phi [°] (Default: None → delta_theta)	n_i = materials.area_factors([0, 15, 30, 45, 60, 75, 90], delta_theta=15.0) • Dimensionless, min 1
random_incidence_diffusion	function	Random-incidence diffusion coefficient d (Clause 8.4). • directional_coefficients: d_θ per source • weights: source weights (Default: None → equal; 2-D uses TWO_DIMENSIONAL_SOURCE_WEIGHTS)	d = materials.random_incidence_diffusion(d_thetas, weights=TWO_DIMENSIONAL_SOURCE_WEIGHTS)
TWO_DIMENSIONAL_SOURCE_WEIGHTS	tuple	ISO 17497-2 single-plane source weights. (1, 3, 3, 3, 3) for 0°, ±30°, ±60°	TWO_DIMENSIONAL_SOURCE_WEIGHTS
ScatteringDiffusionWarning	warning class	ISO 17497 advisory. Emitted for out-of-range scattering/diffusion measurement conditions (e.g. a base plate over the Table 1 limits)	warnings.simplefilter('error', ScatteringDiffusionWarning)
quadratic_residue_sequence	function	Quadratic residue sequence s_n (Cox & D'Antonio Eq. 10.2). • prime: odd prime generator N	quadratic_residue_sequence(7) # [0 1 4 2 2 4 1] • s_n = n² mod N
qrd_well_depths	function	QRD well depths d_n (Cox & D'Antonio Eq. 10.3). • prime: generator N • design_frequency f0 [Hz] • speed_of_sound c [m/s] (Default: 343)	qrd_well_depths(7, 500.0) # d_max 0.196 m • d_n = s_n λ0/(2N)
plot_qrd_geometry	function	To-scale QRD well profile. • depths d_n [m], well_width w [m] • repetitions (Default: 1), fin_width [m] (Default: w/12) • language	plot_qrd_geometry(materials.qrd_well_depths(7, 500.0), 0.12, repetitions=2) • Also DiffuserPolarResponse.plot_geometry()
MetadiffuserWell	dataclass	One slit of a metadiffuser panel (Jiménez et al. Sci. Rep. 2017). • slit_height h [m] • resonators: tuple of HelmholtzResonator, face to backing • None in a well sequence = flat rigid strip (R = 1)	MetadiffuserWell(14.7e-3, (hr, hr)) • lattice a = L/M
metadiffuser_reflection	function	Per-well reflection spectra R_n(f) of a metadiffuser. • frequency f [Hz], wells: MetadiffuserWell/None sequence • depth L, period_m d [m]; angle_deg θ [rad] (Default: 0) • resonator_geometry "slit"/"square" (Default: slit) • 2-D visco-thermal TMM per slit	panel = materials.metadiffuser_reflection(f, wells, depth=0.02, period_m=0.07) • MetadiffuserResult
MetadiffuserResult	dataclass	Metadiffuser spectra, one reflection row per well. • reflection (N, F), well_absorption (N, F) • absorption: face average 1 − mean|R_n|² • retains wells/depth/period_m	panel.plot(); panel.plot_geometry() • .plot() α per well; .plot_geometry() panel section
metadiffuser_polar_response	function	Far-field polar response of a metadiffuser at one frequency. • frequency f [Hz], wells, depth L, period_m d [m] • angles_deg [°], source_angle_deg ψ [°], repetitions (Default: 1) • Fraunhofer of R_n(f), no obliquity factor (Sci. Rep. Eq. (1))	pol = materials.metadiffuser_polar_response(2000.0, wells, depth=0.02, period_m=0.07, repetitions=6) • DiffuserPolarResponse
metadiffuser_diffusion_spectrum	function	Normalized diffusion spectrum d_n(f) of a metadiffuser. • frequencies [Hz], wells, depth L, period_m d [m] • normalised against the same-footprint flat panel • ISO 17497-2 directional coefficient per band	metadiffuser_diffusion_spectrum(f, wells, depth=0.02, period_m=0.07) • DiffusionSpectrum
plot_metadiffuser_panel_geometry	function	To-scale metadiffuser panel cross-section. • wells, depth L, period_m d [m] • numbered slits, resonators shelved into the septum • language	plot_metadiffuser_panel_geometry(wells, depth=0.02, period_m=0.07) • Also MetadiffuserResult.plot_geometry()
predict_diffuser_polar_response	function	Predicted far-field polar response (Cox & D'Antonio Eq. 5.8). • well_width w [m], frequency f [Hz] • depths d_n [m] or reflection R_n (exactly one) • angles_deg [°] (Default: semicircle), source_angle_deg ψ [°] • repetitions Np (Default: 1)	s = materials.predict_diffuser_polar_response(0.10, 2000.0, depths=d, repetitions=5) • DiffuserPolarResponse
predicted_diffusion_spectrum	function	Predicted diffusion spectrum d(f) of a design. • well_width [m], frequencies [Hz] • depths d_n [m] • repetitions (Default: 1) • normalize: also d_n vs flat reference (Default: True)	res = materials.predicted_diffusion_spectrum(0.10, f, depths=d, repetitions=5) • DiffusionSpectrum
DiffuserPolarResponse	dataclass	Predicted diffuser polar response. • frequency [Hz] • angles_deg [°], levels [dB] (peak at 0) • coefficient: d_θ • .plot()	s.coefficient
DEFAULT_POLAR_ANGLES	tuple	ISO 17497-2 single-plane receiver angles. −90° to 90° in 5° steps (37 receivers)	DEFAULT_POLAR_ANGLES[0] # -90
adrienne_window	function	Adrienne temporal window (ISO 13472-1 Clause 6.4). • fs [Hz] • flat_duration [s] (Default: 0.005) • leading_duration [s] (Default: 0.0005), trailing_duration [s] (Default: 0.005) • leading_edge/trailing_edge: 'blackman-harris' or 'cosine-squared'	w = materials.adrienne_window(48000) • Rising edge + flat top + falling edge, peak 1.0
geometric_spreading_factor	function	Geometrical-spreading factor Kr (Clause 4.1). • source_height ds [m] (Default: 1.25) • mic_height dm [m] (Default: 0.25)	geometric_spreading_factor() # 0.6667 • Kr = (ds − dm)/(ds + dm)
geometric_spreading_factor_angle	function	Oblique factor Kr,θ (Annex F). • incidence_angle_rad θ [rad] • source_height, mic_height	geometric_spreading_factor_angle(np.pi/6) # 0.764
reflected_path_delay	function	Reflected-path delay Δτ = 2dm/c (Annex C). • mic_height dm [m] (Default: 0.25) • speed_of_sound c [m/s] (Default: 340.0)	reflected_path_delay() # 0.001471 • [s]
insitu_reflection_factor	function	Complex reflection factor r(f) (ISO 13472-1 Clause 4.1). • incident_ir / reflected_ir: windowed impulse responses • source_height, mic_height [m] • incidence_angle_rad [rad] (Default: 0) • fs + delay: undo the reflected-path offset (Default: None) • n: FFT length	r = materials.insitu_reflection_factor(hi, hr, fs=48000, delay=dtau) • (1/Kr)·Hr(f)/Hi(f) at the rfft bins
insitu_absorption_from_reflection	function	α from the reflection factor (Clause 4.1). • reflection: complex r	alpha = materials.insitu_absorption_from_reflection(r) • α = 1 − |r|²
power_reflection_coefficient	function	Power reflection factor QW(f), direct energy route. • incident_ir, reflected_ir • source_height, mic_height, incidence_angle_rad, n	qw = materials.power_reflection_coefficient(hi, hr) • (1/Kr²)|Hr/Hi|², offset-independent
insitu_absorption_coefficient	function	Narrow-band absorption α(f) (Clause 4.1). • Same parameters as power_reflection_coefficient	alpha = materials.insitu_absorption_coefficient(hi, hr) • α = 1 − QW(f)
one_third_octave_absorption	function	Aggregate narrow-band α into one-third octaves. • frequency [Hz], absorption • f_min (Default: 250), f_max (Default: 4000; 1600 for Part 2) [Hz] • clip_negative (Default: True)	fc, ab = materials.one_third_octave_absorption(f, alpha) • Band centres + linear-averaged α (nan if empty)
insitu_absorption_spectrum	function	End-to-end in-situ spectrum (ISO 13472-1). • incident_ir, reflected_ir, fs [Hz] • geometry + incidence_angle_rad • f_min/f_max [Hz], clip_negative	res = materials.insitu_absorption_spectrum(hi, hr, 48000) • InsituAbsorptionResult
plot_insitu_geometry	function	In-situ absorption set-up to scale. • source_height (Default: 1.25 m), mic_height (Default: 0.25 m) • sampled_radius (Default: 1.34 m) • language	plot_insitu_geometry() • Also InsituAbsorptionResult.plot_geometry()
InsituAbsorptionResult	dataclass	In-situ absorption spectrum. • frequencies: one-third-octave centres [Hz] • absorption: α per band (nan when empty) • .plot()	res.absorption
absorption_reference_corrected	function	Reference-corrected road absorption (Annex B). • road_reflection / reference_reflection: measured Qp (complex, same geometry)	alpha = materials.absorption_reference_corrected(q_road, q_ref) • 1 − |Qp,road/Qp,ref|²; removes chain error and Kr
max_sampled_area_radius	function	Maximum sampled-area radius (Annex A). • window_width Tw [s] • source_height, mic_height, speed_of_sound	max_sampled_area_radius(0.005) # 1.34 • [m], the Annex A worked example
msa_major_axis	function	Major axis of the oblique sampled ellipsoid (Annex F). • window_width Tw [s] • projected_distance dp [m] • source_height, mic_height, speed_of_sound	msa_major_axis(0.005, 0.0) # 3.2 • a = cTw + √((ds + dm)² + dp²) [m]
spot_tube_upper_frequency	function	Spot-tube upper frequency (ISO 13472-2 §5.4.1). • diameter_m d [m] • speed_of_sound (Default: 340.0)	spot_tube_upper_frequency(0.1) # 1972 • f_u = 0.58c0/d [Hz]
spot_microphone_spacing_bounds	function	Spacing bounds (s_min, s_max) (§5.4.2). • speed_of_sound (Default: 340.0) • f_min (Default: 220), f_max (Default: 1800) [Hz]	spot_microphone_spacing_bounds() # (0.0773, 0.085) • [m], brackets the nominal 81 mm
check_spot_frequency_range	function	Advise outside 250–1600 Hz (ISO 13472-2 Scope). • frequency [Hz]	check_spot_frequency_range(f) • RoadAbsorptionWarning out of range
spot_internal_loss_correction	function	Internal-loss (system) correction (Annex A). • measured_absorption, system_absorption: same bands • clip_negative (Default: True)	spot_internal_loss_correction([0.12, 0.10], [0.02, 0.03]) # [0.1, 0.07] • Subtractive Part-2 correction
DEFAULT_SOURCE_HEIGHT	float	ISO 13472-1 mandatory source height ds [m]. 1.25	DEFAULT_SOURCE_HEIGHT # 1.25
DEFAULT_MIC_HEIGHT	float	ISO 13472-1 mandatory microphone height dm [m]. 0.25	DEFAULT_MIC_HEIGHT # 0.25
DEFAULT_SPEED_OF_SOUND	float	Default speed of sound for the road methods [m/s]. 340.0	DEFAULT_SPEED_OF_SOUND # 340.0
PART1_FREQUENCY_RANGE	tuple	ISO 13472-1 valid band range [Hz]. (250.0, 4000.0)	PART1_FREQUENCY_RANGE
SPOT_FREQUENCY_RANGE	tuple	ISO 13472-2 valid band range [Hz]. (250.0, 1600.0)	SPOT_FREQUENCY_RANGE
SPOT_NARROW_BAND_RANGE	tuple	ISO 13472-2 narrow-band range [Hz]. (220.0, 1800.0)	SPOT_NARROW_BAND_RANGE
RoadAbsorptionWarning	warning class	ISO 13472 advisory. Emitted for frequencies outside the valid in-situ road-absorption ranges; results there are advisory	warnings.simplefilter('error', RoadAbsorptionWarning)
frequency_weighting	function	Vibration frequency weighting H(f) (ISO 8041-1:2017 Formula 5). • name: one of WEIGHTING_NAMES • frequencies [Hz] (> 0)	wr = vibration.frequency_weighting('Wk', [1.0, 8.0, 63.0]) • WeightingResponse; |H| = [0.482, 1.036, 0.186]
weighting_factors	function	Weighting factors |H(f)| (the Wi of ISO 2631-1 Eq. 9). • name, frequencies [Hz]	weighting_factors('Wh', [16.0]) • Magnitude per frequency
apply_weighting	function	Apply a weighting to a time signal (frequency domain, exact response). • signal: acceleration (1D) [m/s²] • fs [Hz] • name: one of WEIGHTING_NAMES	aw_t = vibration.apply_weighting(a, fs, name="Wk") • Weighted signal, same length (circular FFT filtering)
WeightingResponse	dataclass	Weighting response. • name • frequencies [Hz] • response: complex H • magnitude, magnitude_db [dB] • .plot()	wr.magnitude, wr.magnitude_db
WEIGHTING_NAMES	tuple	ISO 8041-1 weighting names. ('Wb', 'Wc', 'Wd', 'We', 'Wf', 'Wh', 'Wj', 'Wk', 'Wm')	'Wk' in WEIGHTING_NAMES # True
weighted_acceleration	function	Weighted r.m.s. from a band spectrum (ISO 2631-1 Eq. 9 / ISO 5349-1 Eq. A.1). • band_accelerations: ai per band [m/s²] • frequencies: band centres [Hz] • weighting: name	ws = vibration.weighted_acceleration([0.1, 0.3, 0.2], [4.0, 8.0, 16.0], 'Wk') • WeightedSpectrum; aw = 0.36 m/s²
WeightedSpectrum	dataclass	Weighted band spectrum. • frequencies [Hz], band_accelerations [m/s²] • weighting_name, weighting_factors • weighted: Wi·ai [m/s²] • overall: aw [m/s²] • .plot()	ws.overall
running_rms	function	Running r.m.s. of a weighted signal (ISO 2631-1 Eqs. 2/3). • signal [m/s²], fs [Hz] • integration_time τ [s] (Default: 1.0) • method: 'linear' (Eq. 2) or 'exponential' (Eq. 3) (Default: 'linear')	env = vibration.running_rms(aw_t, fs) • aw(t0) per sample [m/s²]
mtvv	function	Maximum transient vibration value (Eq. 4). • signal [m/s²], fs [Hz] • integration_time [s] (Default: 1.0)	mtvv(aw_t, fs) • max aw(t0) [m/s²]
vibration_dose_value	function	Vibration dose value VDV (Eq. 5). • signal: weighted acceleration [m/s²] • fs [Hz]	vdv = vibration.vibration_dose_value(aw_t, fs) • (∫aw⁴dt)^(1/4) [m/s^1.75]
motion_sickness_dose_value	function	Motion sickness dose value MSDV (ISO 2631-1 clause 9). • signal: Wf-weighted acceleration [m/s²] • fs [Hz]	msdv = vibration.motion_sickness_dose_value(aw_t, fs) • (∫aw²dt)^(1/2) [m/s^1.5]
crest_factor	function	Crest factor of a weighted signal (clause 6.2.1). • signal [m/s²]	crest_factor(aw_t) • peak/r.m.s.; HumanVibrationWarning above 9
vibration_total_value	function	Vibration total value av/ahv (ISO 2631-1 Eq. 10). • components: axis-weighted r.m.s. [m/s²] • k: per-axis factors (Default: None → 1, the ISO 5349-1 vector sum)	vibration_total_value([0.3, 0.4, 0.5], k=[1.4, 1.4, 1.0]) # 0.86 • √(Σ kj²awj²) [m/s²]
wbv_exposure_basis	function	Whole-body A(8) basis of Directive 2002/44/EC (Annex Part B). • a_wx, a_wy: Wd-weighted axis r.m.s. [m/s²] • a_wz: Wk-weighted axis r.m.s. [m/s²]	wbv_exposure_basis(0.35, 0.28, 0.62) # 0.62 • max(1.4·awx, 1.4·awy, awz) [m/s²], the dominant axis (not the vector total av)
daily_exposure	function	Daily exposure A(8) for one operation (ISO 5349-1 Eq. 2). • total_value: ahv (hand-arm) or aw,max (whole-body) [m/s²] • duration_s: T [s]	daily_exposure(3.0, 4*3600) # 2.12 • ahv √(T/8h) [m/s²]
partial_exposure	function	Partial exposure Ai(8) of one operation (Eq. 2). • total_value [m/s²], duration_s [s]	partial_exposure(3.0, 2*3600) # 1.5
combine_partial_exposures	function	Combine partial exposures (Eq. 3). • partials: Ai(8) [m/s²]	combine_partial_exposures([1.5, 2.1]) # 2.58 • √(Σ Ai(8)²) [m/s²]
hav_daily_exposure	function	A(8) for several operations (ISO 5349-1 Eq. 3). • total_values: ahvi [m/s²] • durations_s: Ti [s]	hav_daily_exposure([3.0, 5.0], [2*3600, 3600]) # 2.32
energy_equivalent_acceleration	function	Energy-equivalent magnitude aw,e (ISO 2631-1 Eq. B.3). • magnitudes [m/s²], durations_s [s]	energy_equivalent_acceleration([0.5, 1.0], [3600, 1800]) # 0.707
hav_vwf_lifetime_years	function	Years to 10 % vibration-white-finger prevalence (ISO 5349-1 Eq. C.1). • a8: A(8) [m/s²] (> 0)	hav_vwf_lifetime_years(2.5) # 12.0 • Dy = 31.8 A(8)^−1.06 [years]
exposure_assessment	function	Assess a daily exposure (Directive 2002/44/EC Article 3). • value: A(8) [m/s²] or VDV [m/s^1.75] • kind: 'hav'/'wbv' • metric: 'a8' (Default) or 'vdv' (whole-body only)	ea = vibration.exposure_assessment(3.0, kind='hav') • ExposureAssessment (zone 'action')
ExposureAssessment	dataclass	Directive assessment. • value, kind, metric • action_value (EAV), limit_value (ELV) • exceeds_action, exceeds_limit • zone: 'below action'/'action'/'limit'	ea.zone, ea.exceeds_limit
daily_vibration_exposure	function	A(8) from several operations, assessed (ISO 5349 + Directive). • total_values [m/s²], durations_s [s] • kind: 'hav'/'wbv' • labels (Default: None → 'op 1', …)	res = vibration.daily_vibration_exposure([3.0, 5.0], [2*3600, 3600], kind='hav') • DailyVibrationExposure (A(8) = 2.32)
DailyVibrationExposure	dataclass	Assessed daily exposure. • a8 [m/s²] • labels, total_values, durations_s, partials • assessment: ExposureAssessment • .plot()	res.a8, res.assessment.zone
HumanVibrationWarning	warning class	Human-vibration advisory. Emitted for a crest factor above 9 (ISO 2631-1 6.2.2) or other out-of-range measurement conditions	warnings.simplefilter('error', HumanVibrationWarning)
verify_weighting / WeightingVerification	function / dataclass	Does a vibration meter's frequency weighting meet ISO 8041-1 (Tables 4 and 5)? • name, frequencies [Hz], measured_factors (linear, not dB) • expanded_uncertainty_percent: the testing laboratory's own U, which extends the measured deviation (13.1 and 14.1); Default None, the bare deviation • .passes, .deviation_percent, .failing_frequencies_hz, .worst_deviation_percent, .expanded_uncertainty_percent, .plot() • the weighting only: indication, linearity, overload and the environmental tests are hardware measurements this does not stand in for	vibration.verify_weighting('Wk', [16.0], [0.86]).passes # True (+11.9 %, inside +12 %)
verify_phase_response / PhaseVerification	function / dataclass	Does its phase response meet the phase column of ISO 8041-1 Table 5? • name, frequencies_hz (ascending), measured_phase_deg on the continuous branch Annex B prints • .characteristic_deviation_deg (Formula (6), one per adjacent pair, attributed to the lower frequency), .deviation_deg, .tolerance_deg, .passes, .peak_deviation_percent, .plot() • only for a meter reporting a parameter not based on r.m.s. values (Table 5 footnote a)	vibration.verify_phase_response('Wk', [8.0, 10.0, 12.5], phases).passes
characteristic_phase_deviation / peak_deviation_percent	function	The two formulae the phase criterion is made of. • Formula (6): abs((f_n Δφ_{n+1} − f_{n+1} Δφ_n) / (f_{n+1} − f_n)) [degrees], N − 1 values • Formula (H.4): the peak-value deviation that costs, 0,48 sin Δφ0 × 100 %, an approximation Annex H limits to Δφ0 below 30°	vibration.peak_deviation_percent(12.0) # 9.98 %
NOMINAL_FREQUENCY_RANGE_HZ	constant	The nominal frequency range of each weighting (ISO 8041-1 Table 1). • Wh 8 to 1 000, whole-body 0,5 to 80, Wm 1 to 80, Wf 0,1 to 0,5 • the printed round numbers, not the band centres 10**(k/10) Annex B tabulates at	vibration.NOMINAL_FREQUENCY_RANGE_HZ['Wm'] # (1.0, 80.0)
ISO8041_COVERAGE_FACTOR / MAX_EXPANDED_UNCERTAINTY_PERCENT	constant	What a testing laboratory's uncertainty is expanded with, and how far it may reach. • k = 2 (13.1 and 14.1; 12.1 prints "no less than 2"), named for its standard because hearing.COVERAGE_FACTOR is a different one (1,65, ISO 9612) • the maximum permitted expanded uncertainty per test clause, e.g. 4,5 % for 12.11.2 and 0,01 % for the timing clauses	vibration.MAX_EXPANDED_UNCERTAINTY_PERCENT['12.13'] # 3.0 %
PVEM_MAX_EXPANDED_UNCERTAINTY_PERCENT	constant	The same limits for a personal vibration exposure meter (ISO 8041-2:2021 clauses 12 and 13). • keyed by the Part 2 clause number: 11 figures over 10 clauses (12.10.2 prints one for the reference range and one for the other ranges), each 12.x figure the one Part 1 prints for the same clause • 13.9 is Part 2's periodic verification (5 %), not Part 1's one-off indication test (2 %), which is why each part has its own table	vibration.PVEM_MAX_EXPANDED_UNCERTAINTY_PERCENT['12.11.2'] # 4.5 %
weighting_tolerance_percent / phase_tolerance_degrees	function	The band ISO 8041-1 Table 5 allows, region by region. • +12 % / −11 % in the central region, +26 % / −21 % in the skirts, no lower limit in the tails • the phase band applies only to a meter reporting a parameter not based on r.m.s. values (Table 5 footnote a), which is why it is a separate call	vibration.weighting_tolerance_percent('Wk', [16.0]) # (12.0, -11.0)
TRANSITION_FREQUENCIES_HZ / CENTRAL_TOLERANCE_PERCENT / SKIRT_TOLERANCE_PERCENT / TAIL_TOLERANCE_PERCENT / UNCONSTRAINED_BELOW	constant	Tables 4 and 5 of ISO 8041-1, as data. • the four transition frequencies per weighting, built from the printed 10**(k/10) exponents • the three bands, each (upper %, lower %, phase °) • −100 %, which is the absence of a lower limit rather than a wide one	vibration.TRANSITION_FREQUENCIES_HZ['Wk'] • (0.251, 0.631, 63.1, 158.5) Hz
REFERENCE_FREQUENCY_HZ / REFERENCE_ACCELERATION_M_S2 / reference_indication	constant / function	The ISO 8041-1 Table 1 reference conditions. • the calibration frequency per weighting, from the radians per second the standard prints • the reference r.m.s. acceleration, 1 m/s² whole-body, 10 hand-transmitted, 0,1 low-frequency • reference_indication(name) is their product with the weighting factor there, which is what a conforming meter shows	vibration.reference_indication('Wh') # 2.02 m/s²
indication_tolerance_percent / INDICATION_TOLERANCE_PERCENT / LOW_FREQUENCY_INDICATION_TOLERANCE_PERCENT / LOW_FREQUENCY_WEIGHTING	function / constant	How far the indication itself may sit from the truth (ISO 8041-1 Table 2). • 4 % at the reference frequency, and 5 % for the low-frequency whole-body case, which is Wf	vibration.indication_tolerance_percent('Wf') # 5.0
PVEM_INDICATION_TOLERANCES_PERCENT	constant	Table 2 of a personal vibration exposure meter (ISO 8041-2:2021). • 'indication' 4 %, 'low-frequency indication' 5 %, 'weighting consistency' 3 %: the first two rows of the Part 1 table • no running r.m.s. row, because Part 2 5.13 declares the running r.m.s. not applicable to a PVEM	vibration.PVEM_INDICATION_TOLERANCES_PERCENT['weighting consistency'] # 3.0
band_limiting_response / band_limiting_factors / apply_band_limiting	function	The band-limiting stage of a weighting on its own (ISO 8041-1 Formulae (1) and (2)). • the two-pole Butterworth high-pass and low-pass pair every weighting starts with, without the transition and step stages • apply_band_limiting(signal, fs=None, *, name) filters with it, which is what the band-limiting row of the burst tables is measured on	vibration.band_limiting_factors('Wk', [1.0]) • 0.9874
band_limited_weighting_factor / WEIGHTING_CONSISTENCY_TOLERANCE_PERCENT	function / constant	The weighting factor a band-limited channel actually shows (ISO 8041-1 Table 2, row 2). • the design goal times the band-limiting response, which is what a meter indicates when both stages are in the path • the 3 % row 2 allows between the two	vibration.band_limited_weighting_factor('Wk', [16.0])
running_rms_decay_time	function	How long the running r.m.s. takes to fall to 10 % of its steady value (ISO 8041-1 5.13). • integration_time_s, and method selecting linear or exponential averaging • the quantity Table 11 prints, timed from the moment the signal is shut off	vibration.running_rms_decay_time(1.0, method='linear')
verify_running_rms_decay / RunningRmsDecayVerification / RUNNING_RMS_DECAY_RATE_DB_PER_S / RUNNING_RMS_DECAY_TIME_S / RUNNING_RMS_CONSISTENCY_TOLERANCE_PERCENT	function / dataclass / constant	Does the running r.m.s. decay at the printed rate (ISO 8041-1 Tables 10 and 11)? • measured_time_s, with integration_time_s and method keyword-only • .passes, .printed_time_s, .tolerance_s, .lower_time_s, .upper_time_s, .deviation_s, .plot() • the decay in decibels per second and the time to fall, per integration time, for linear and exponential averaging • the 2 % the indication may differ by	vibration.RUNNING_RMS_DECAY_RATE_DB_PER_S[1] • (1.0, 3.8, 4.9) s, dB, dB
verify_signal_burst_response / SignalBurstVerification	function / dataclass	A meter's response to the saw-tooth burst of ISO 8041-1 5.9 (Tables 7 to 9). • application, weighting, the measured indications per burst length • .passes, .deviation_percent, .failing_cycle_counts, .plot() • graded on a zero-state simulation, which is what the printed tables come from	vibration.verify_signal_burst_response('whole-body', 'Wk', measured)
sawtooth_burst / signal_burst_indications / SawtoothBurstTest / SAWTOOTH_BURST_TESTS	function / dataclass / constant	The burst signal itself and what a conforming meter reads from it (Table 6). • sawtooth_burst(...) builds the waveform: angular frequency, start time, cycle count, repeat and total duration • the three applications, 500 rad/s hand-arm, 100 whole-body and 2,5 low-frequency	vibration.SAWTOOTH_BURST_TESTS['whole-body'].cycle_counts • (1, 2, 4, 8, 16)
SIGNAL_BURST_RESPONSE / BURST_TOLERANCE_PERCENT / BAND_LIMITING	constant	Tables 7, 8 and 9 as data, and the tolerance each column carries. • 228 printed cells keyed by (application, weighting, cycles), with None for the continuous row • 10 % on the r.m.s. and MTVV columns, 12 % on VDV • 'band-limiting' names the row measured with the weighting stages out of the path	vibration.BURST_TOLERANCE_PERCENT['vdv'] # 12.0
REFERENCE_ACCELERATION	float	Vibration reference acceleration [m/s²]. 1e-6 (ISO 1683 acceleration level reference)	REFERENCE_ACCELERATION # 1e-06
REFERENCE_DURATION_S	float	Daily-exposure reference duration T0 [s]. 28800 (8 h)	REFERENCE_DURATION_S # 28800.0
HAV_EAV_A8	float	Hand-arm exposure action value [m/s²]. 2.5 (Directive 2002/44/EC)	HAV_EAV_A8 # 2.5
HAV_ELV_A8	float	Hand-arm exposure limit value [m/s²]. 5.0	HAV_ELV_A8 # 5.0
WBV_EAV_A8	float	Whole-body A(8) action value [m/s²]. 0.5	WBV_EAV_A8 # 0.5
WBV_ELV_A8	float	Whole-body A(8) limit value [m/s²]. 1.15	WBV_ELV_A8 # 1.15
WBV_EAV_VDV	float	Whole-body VDV action value [m/s^1.75]. 9.1	WBV_EAV_VDV # 9.1
WBV_ELV_VDV	float	Whole-body VDV limit value [m/s^1.75]. 21.0	WBV_ELV_VDV # 21.0
measure_vibration_immission / VibrationMeterReading	function / dataclass	What a DIN 45669-1 vibration meter displays for one record (5.1.6). • velocity_mm_s [mm/s], fs_hz [Hz] • keyword-only: working_range ('building' 1-80 Hz, Default; 'railway' 4-315 Hz), takt_duration_s (Default: 30) • .peak_velocity_mm_s, .kbf, .kbf_max, .takt_maxima, .kbf_takt_rms, .measuring_time_s, .averaging_time_s, .above_detection_limit, .plot() • start the record before the event: a record that opens at full amplitude leaves the filter's switch-on transient in the max-hold	r = vibration.measure_vibration_immission(v, 2048.0) • r.kbf_max, r.kbf_takt_rms
kb_signal / kbf_signal	function	The KB signal and the weighted vibration severity (3.10.1, Formula (1)). • KB(t) is the velocity band-limited, frequency-weighted and normalised by 1 mm/s, so it is dimensionless • KB_F(t) is its running r.m.s. with τ = 0,125 s ("Fast") • keyword-only: working_range, and time_constant_s for a comparison the standard does not allow a meter	vibration.kbf_signal(v, 2048.0).max() # KB_Fmax
takt_maxima / takt_maximum_rms	function	The clock maxima and their r.m.s., Formula (2). • one maximum per whole 30 s clock interval; a part-interval is dropped (5.1.6.4) • a maximum at or below 0,1 enters the sum as zero and its interval still counts in N	vibration.takt_maximum_rms([0.8, 0.05]) # 0.566
band_limitation_response / kb_weighting_response	function	Formulae (3) and (4), complex, at the frequencies asked for. • two-pole Butterworth pairs at 0,8 f_u and f_o / 0,8, and the 5,6 Hz pole that makes the KB weighting • the magnitudes are Formulae (5) and (6)	abs(vibration.kb_weighting_response([16.0])) # 0.944
verify_vibration_meter / VibrationMeterVerification	function / dataclass	Does a meter's amplitude response meet DIN 45669-1 Tables 2 and 3? • frequencies_hz, measured_response (any consistent unit: only the shape is graded) • keyword-only: weighting ('kb' Default, or 'unweighted'), working_range, reference_frequency_hz (Default: 16) • .deviation_percent (Formula (7)), .lower_percent, .upper_percent, .within_tolerance, .passes, .worst_frequency_hz, .plot() • the response only: Clause 6 also asks for linearity, overload and the environmental tests	vibration.verify_vibration_meter(f, measured).passes
response_tolerance_percent / RESPONSE_TOLERANCE_LOWER_PERCENT / RESPONSE_TOLERANCE_UPPER_PERCENT	function / constant	Tables 2 and 3, as bands of the working range. • 10 % from 1,25 f_u to 0,8 f_o, 20 % out to 0,5 f_u and 2 f_o • 100 % below that band is the absence of a lower limit, and the upper limit applies only where the response is above 0,01	vibration.response_tolerance_percent([100.0]) • (20.0, 20.0) %
assessment_weighting_response / assessment_weighting_taps	function	The three Annex E weighting filters (Table E.1). • the target magnitude is the guideline curve of DIN 4150-3 Table 1 inverted and normalised to its 1-10 Hz value • assessment_weighting_taps(fs_hz, *, building_class, numtaps=None) designs the symmetric FIR the annex asks for, which has the linear phase a peak measurement needs	vibration.assessment_weighting_response([50.0], building_class='residential') • 0.333
assessment_velocity / assess_short_term_vibration / AssessmentVelocity	function / dataclass	Short-term vibration on a building judged without a dominant frequency (Annex E). • velocity_mm_s [mm/s], fs_hz [Hz], keyword-only building_class and numtaps • .assessment_velocity_mm_s = |v_Bn|max, .guide_value_mm_s, .ratio, .within_guideline, .plot() • the verdict reads like DIN 4150-3: keeping to the value is what the standard promises about, exceeding it moves the question to Clauses 4.2 to 4.4	vibration.assess_short_term_vibration(v, 2048.0, building_class='residential').within_guideline
dominant_frequency / DominantFrequency	function / dataclass	The dominant frequency of a short-term event (Annex D). • method='zero_crossing' (Default: the crossings around the largest amplitude are half a period apart) or 'fourier' • .frequency_hz, .method, .candidates (the two largest spectral values, Fourier only) • the two can disagree, which is the ambiguity Annex E removes	vibration.dominant_frequency(v, 2048.0).frequency_hz
WORKING_RANGES_HZ / BAND_LIMIT_CORNER_FACTOR / KB_CORNER_HZ / KB_TIME_CONSTANT_S	constant	The four numbers the chain is built from (5.2.3, 3.10.1.2). • 1 Hz to 80 Hz for buildings and 4 Hz to 315 Hz next to a railway • the 0,8 between a band limit and its filter corner, the 5,6 Hz of the weighting and the 0,125 s of the running r.m.s.	vibration.WORKING_RANGES_HZ['railway'] # (4.0, 315.0)
TAKT_DURATION_S / TAKT_SUPPRESSION_THRESHOLD / KB_DETECTION_LIMIT / VELOCITY_DETECTION_LIMIT_MM_S	constant	The clock interval and the limits below which a meter promises nothing. • 30 s per clock interval (5.1.6.4), and the 0,1 of Formula (2) • 0,05 mm/s on the peak velocity and 0,02 on the weighted vibration severity (5.2.2)	vibration.TAKT_DURATION_S # 30.0
KB_REFERENCE_FREQUENCY_HZ / KB_REFERENCE_INDICATIONS / KB_INDICATION_TOLERANCE_PERCENT	constant	The reference conditions of 5.2.10 and what they must show (6.2.3.12). • a 1 mm/s sine at 16 Hz, and the four values it produces: 1,00 mm/s, 0,667, 0,680 and 0,680 • 4 % is how far the display may sit from them	vibration.KB_REFERENCE_INDICATIONS['kbf_max'] # 0.68
KB_TEST_INDICATIONS / KB_PULSE_RESPONSE_PERCENT	constant	Table 9 and Table 8, as data. • the KB_F, KB_Fmax and KB_FTm a 1 mm/s sine shows at 1, 5,6, 31,5, 80 and 315 Hz • Corrigendum 1's redraft of the burst table: eight burst durations of an 80 Hz sine and the KB_Fmax each shows as a percentage of the continuous display • the |v|max row of Table 9 is not here; it contradicts Formula (5), see docs/ERRATA.md	vibration.KB_TEST_INDICATIONS[31.5] • (0.693, 0.7, 0.7)
ASSESSMENT_GUIDE_VALUES_MM_S / ASSESSMENT_WEIGHTING_TOLERANCE	constant	Table E.2 and the band Table E.1 allows a realised filter. • 20, 5 and 3 mm/s, one per building class, independent of frequency • 5 % either side of the target magnitude	vibration.ASSESSMENT_GUIDE_VALUES_MM_S['sensitive'] # 3.0
check_loose_mounting / MountingCheck	function / dataclass	May the transducer be set down without fastening? (DIN 45669-2 5.3.2, 5.3.3) • peak_acceleration_m_s2 [m/s²], upper_frequency_hz [Hz], keyword-only direction ('vertical' or 'horizontal') and surface ('hard' Default, 'soft') • .acceptable, .frequency_limit_hz (100 vertical, 40 horizontal), .peak_acceleration_limit_m_s2 (3), .device (what it stands on: rounded feet, or the spiked device on a covering)	vibration.check_loose_mounting(1.2, 63.0, direction='horizontal').acceptable # False
instrument_confidence_limit_percent / INSTRUMENT_CONFIDENCE_LIMITS_PERCENT	function / constant	Table 3 of DIN 45669-2: how far a conforming meter may still be from the truth. • quantity 'rms' (15 %, 25 %) or 'peak' (20 %, 35 %), accuracy_class 1 (Default) or 2 • the classes are those of the 1995 Part 1; the 2010 edition dropped them, so class 1 is the column for a meter of today	vibration.instrument_confidence_limit_percent('peak') # 20.0
mass_loading_ratio / MASS_LOADING_RATIO_LIMIT	function / constant	7.2.4: the mass the transducer adds to the object, at most a hundredth. • coupled_mass_kg [kg], keyword-only vibrating_mass_kg [kg] • the ratio to compare with 0.01	vibration.mass_loading_ratio(2.5, vibrating_mass_kg=600.0) # 0.0042
LOOSE_MOUNTING_LIMITS_HZ / LOOSE_MOUNTING_PEAK_ACCELERATION_M_S2 / WAX_MOUNTING_HORIZONTAL_LIMIT_HZ / SPIKED_DEVICE_MASS_KG	constant	The mounting numbers of DIN 45669-2. • 100 Hz vertically and 40 Hz horizontally for a loose transducer, at up to 3 m/s² peak • 80 Hz for the horizontal component on a sensitive hard surface with adhesive wax (Table 1) • about 2.5 kg for the spiked device with the transducer (5.3.3.1)	vibration.LOOSE_MOUNTING_LIMITS_HZ['horizontal'] # 40.0
GROUND_COUPLING_DEVIATION_DB / EMISSION_POINT_TRACK_DISTANCE_M / CLEARANCE_TO_DISTURBING_BODY_FACTOR	constant	The placement numbers of 5.1.4 and 5.3.4.1. • up to 15 dB from the ground coupling alone • 8 m from the nearest track for a railway emission point, and at least 1.5 times the largest dimension of a disturbing body away from it	vibration.GROUND_COUPLING_DEVIATION_DB # 15.0
assess_people_in_buildings / PeopleAssessment	function / dataclass	The verdict of DIN 4150-2 Clause 6.2 on one immission (Figure 2). • kb_fmax, guide (a GuideValues), keyword-only kb_ftr (needed only when the verdict comes down to it), source ('general' Default, 'road', 'railway', 'urban_railway', 'quarry_blasting'), rare_short_events • KB_Fmax at or below A_u is met, and so, as a rule, is one above it by less than the 15 % of 5.4 (Example 3), flagged in .within_uncertainty; above A_o is not, unless the source is a railway or the events are rare; between, KB_FTr against A_r • .complies, .criterion ('A_u', 'A_o' or 'A_r'), .within_uncertainty, .plot() • compared at the decimals the guide value is printed with, half up, which is how Example 4 reads 0,154 as 0,15	vibration.assess_people_in_buildings(0.47, g, kb_ftr=0.154).complies # True
guide_values / GuideValues / GUIDE_VALUES	function / dataclass / constant	Table 1: the guide values by kind of area, day and night. • area 'industrial', 'commercial', 'mixed', 'residential' or 'sensitive'; keyword-only time_of_day ('day' Default, 'night') and source • .a_u, .a_o, .a_r; an urban surface railway raises A_u and A_r by 1,5 (6.5.3.3); quarry blasting under the conditions of 6.5.1 takes the daytime A_o of row 1 in a mixed or residential area	vibration.guide_values('residential').a_r # 0.07
construction_guide_values / CONSTRUCTION_GUIDE_VALUES / CONSTRUCTION_STAGES	function / constant	Table 2: a construction site by working days and stage, with the interpolation of Figure 3. • duration_days, whole working days 1 to 78, keyword-only stage ('I' Default, 'II', 'III') and area (not 'sensitive', to which 6.5.4.2 says the table does not apply) • 2 to 6 days interpolated between the one-day column and the column that starts at 7, at the two decimals Figure 3 prints; A_o 5, or 6 in a commercial or industrial area	vibration.construction_guide_values(4).a_u # 0.6
assessment_vibration_severity / admissible_exposure_s	function	Formulae (4a), (4b) and (5): KB_FTr over the assessment period, and the exposure A_r allows. • kb_ftm and exposure_s [s], one per stretch; keyword-only time_of_day and in_rest_time (weight 2, day only) • admissible_exposure_s(kb_ftm, a_r) is (4b) turned around, as Example 2 does it	vibration.assessment_vibration_severity([0.16, 0.39], [21600, 5400]) # 0.154
railway_takt_maximum_rms / railway_takt_spread / railway_assessment_severity / RailwayAssessment / admissible_trains_per_hour	function / dataclass	Annex A: a railway by classes of train, and Figure D.1. • (A.1) KB_FTm over the clock intervals a class occupies, (A.2) the spread of its square, (A.3) KB_FTr weighted by the intervals each class occupies of the 1920 or 960 of the period, with .lower and .upper from a spread • admissible_trains_per_hour(kb_ftm, a_r) = 120 (A_r / KB_FTm)², one interval per train	vibration.railway_assessment_severity([0.82, 0.22], [288, 192]).kb_ftr # 0.325
kb_from_peak_velocity / kb_fmax_from_peak_velocity / PEAK_TO_KB_FACTORS	function / constant	Clause 7: an estimate of KB_Fmax from an unweighted record, Formulae (6) and (7) with Table 3. • peak_velocity_mm_s [mm/s], frequency_hz [Hz], keyword-only kind (the row of Table 3, 'harmonic' to 'single_event') • KB = v_max / (√2 √(1 + (5,6 Hz / f)²)), times c_F	vibration.kb_fmax_from_peak_velocity(4.0, 14.0, kind='single_event_resonant') # 2.10
ASSESSMENT_PERIOD_S / ASSESSMENT_TAKT_COUNT / DAY_REST_TIME_S / REST_TIME_WEIGHT / KB_UNCERTAINTY_PERCENT	constant	The times and the weights of DIN 4150-2. • 16 h by day and 8 h by night (3.7.3), 1920 and 960 clock intervals (Annex A) • 4 h of rest hours in the day (3.7.4), the weight 2 of Formula (5), the 15 % of 5.4	vibration.ASSESSMENT_TAKT_COUNT['night'] # 960
RARE_EVENTS_PER_DAY / BLASTING_EXCEPTION_KB_FMAX / CONSTRUCTION_BLASTING_A_O / URBAN_RAILWAY_FACTOR / RAILWAY_NIGHT_INVESTIGATION_KB	constant	The source-specific numbers of 6.5. • up to 3 short events a day are judged on A_o alone; quarry blasting under the conditions of 6.5.1 may reach 8 a few times a year; a site's blasting is held to A_o = 8 • 1,5 on A_u and A_r for an urban surface railway; by night a clock maximum above 0,6 on a surface line or 0,3 underground is a reason to look into the cause (6.5.3.5)	vibration.URBAN_RAILWAY_FACTOR # 1.5
GUIDE_VALUES_2023 / ROAD_EXISTING_TOLERANCE_FACTOR / ROAD_NIGHT_INVESTIGATION_KB / INDUCED_SEISMIC_PEAK_FACTOR / BLASTING_MAX_PER_WEEK / induced_seismic_kb_fmax	constant / function	What E DIN 4150-2:2023-08 changes: Table 1 with the night A_u of a mixed area at 0,1, and two sources of its own. • guide_values(..., edition='2023') reads the draft, and its GuideValues carry the edition and the period, which assess_people_in_buildings follows: no shortcut inside the 15 % above A_u, a railway compared with A_o and a road by night not, with a clock maximum above 0,6 as a reason to look into the cause (6.5.2), source='road_existing' with A_u and A_r tolerated 1,5 times over (6.5.2), source='induced_seismic' held by night to the daytime A_o (6.5.1.3) • induced_seismic_kb_fmax(peak_velocity_mm_s) = 0,44 v_max; at most 15 blasts a week where successive ones count as one	vibration.guide_values('mixed', time_of_day='night', edition='2023').a_u # 0.1
train_category_rms / train_kb_fmax / railway_kb_fmax	function	E DIN 4150-2:2023-08 6.5.3.2, Formulae (5), (7) and (8): a railway by category of train. • train_category_rms(kb_fti_zug): the r.m.s. of one clock maximum per passage, nothing zeroed below 0,1 • train_kb_fmax(kb_ftm_zug): 1,5 times the r.m.s. of each category; railway_kb_fmax the largest of them, the KB_Fmax of the line	vibration.train_category_rms([0.379, 0.369, 0.348]) # 0.366
train_assessment_severity / train_weighting_factor / TRAIN_WEIGHTING_FACTORS / TRAIN_KINDS / TRAIN_KB_FMAX_FACTOR	function / constant	Formula (6) and Table 2 of the draft, and Formula (11) and Table E.1 of E DIN 45672-3:2023-02. • train_assessment_severity(kb_ftm_zug, trains, *, alpha, time_of_day): each category weighted by its trains out of the 1920 or 960 intervals and by alpha; a category at or below 0,1 counts as zero • train_weighting_factor(kind, *, alignment): 0,7 for a tram on the surface to 1,3 for a freight train over 600 m	vibration.train_assessment_severity([0.24, 0.44], [28, 8], alpha=[0.9, 1.0]) # 0.039
railway_guide_values / RAILWAY_NEW_LINE_NIGHT_A_O / assess_railway_change / RailwayChange / RAILWAY_CHANGE_TOLERANCE_PERCENT	function / constant / dataclass	6.5.3.5 and 6.5.3.6 of the draft: a line to be built new, and one to be altered. • railway_guide_values(area, *, time_of_day, alignment): Table 1 with the night A_o of a new line, 0,6 on the surface, 0,3 underground outside an industrial or commercial area • assess_railway_change(*, kb_fmax_before, kb_fmax_after, kb_ftr_before, kb_ftr_after, guide, time_of_day): met where the planned case keeps to A_u, or to A_o and A_r, or exceeds those by an increase under 25 %, every condition that applies holding, as the draft's Example 9 does; .complies, .kb_fmax_met, .kb_ftr_met, .kb_ftr_increase_percent	vibration.railway_guide_values('mixed', time_of_day='night').a_o # 0.6
predict_floor_spectrum / predict_train_category / TrainCategoryPrediction	function / dataclass	E DIN 45672-3:2023-02 Formula (1) and the chain of Clause 7: the spectrum a floor will feel, and the KB values from it. • predict_floor_spectrum(emission_db, *, ground_db, foundation_db, floor_db, mitigation_db): every term added, band by band, so a mitigation goes in negative • predict_train_category(emission_db, *, frequencies_hz, ...) runs (1), the Table 2 weighting (8), the sum (9), 1,5 times it (10) and 3 times that (12): .floor_db, .weighted_db, .sum_level_db, .kb_ftm, .kb_fmax, .peak_velocity_mm_s, .plot()	vibration.predict_train_category(emission, ground_db=bb, floor_db=df).kb_ftm
kb_weighted_levels_db / takt_maximum_kb / peak_velocity_from_kb_mm_s / velocity_spectrum_um_s / KB_WEIGHTING_TABLE_DB / KB_ASSESSMENT_BANDS_HZ / TAKT_MAXIMUM_FACTOR / PEAK_VELOCITY_FACTOR	function / constant	Clause 7 of E DIN 45672-3 piece by piece. • Table 2, the KB weighting rounded to a tenth of a decibel from 4 Hz to 80 Hz, added by kb_weighted_levels_db(levels_db, frequencies_hz) • takt_maximum_kb(weighted_levels_db) = c_T1 v_0 10^(L/20) with c_T1 = 1 and v_0 = 5·10⁻⁵ mm/s (Formula (9)); peak_velocity_from_kb_mm_s(kb_fmax_zug) = 3 times it (Formula (12)); velocity_spectrum_um_s(levels_db) in micrometres per second (Formula (13))	vibration.takt_maximum_kb([78.1]) # 0.4018
rescale_emission_for_speed / ground_transmission_db / ground_attenuation_coefficient_per_m / SPEED_RESCALING_LIMIT / GEOMETRIC_DECAY_EXPONENT_RANGE	function / constant	Clauses 5.2 and 5.3 of E DIN 45672-3: the emission at another speed and the way through the ground. • rescale_emission_for_speed(levels_db, *, speed_from_km_h, speed_to_km_h): 20 lg of the ratio, for a change of up to 30 % (Formula (3)) • ground_transmission_db(frequencies_hz, *, distance_m, reference_distance_m, exponent, damping_ratio, shear_wave_speed_m_s): spreading with n, usually 0,2 to 0,4 on the surface, and damping with alpha_R = 2π f D / c_s (Formulae (4) to (6))	vibration.ground_transmission_db([8.0], distance_m=20.0, reference_distance_m=10.0, exponent=0.3) # -1.81
ground_to_floor_transfer_db / ground_to_foundation_transfer_db / foundation_to_floor_transfer_db / GROUND_TO_FLOOR_DB / GROUND_TO_FOUNDATION_DB / FOUNDATION_TO_FLOOR_DB / FOUNDATION_TO_FLOOR_RATIOS / FLOOR_NATURAL_FREQUENCIES_HZ / PREDICTION_BAND_CENTRES_HZ	function / constant	Annex A of E DIN 45672-3: the six tables of level differences into and inside a building. • ground to floor (Tables A.1 and A.2) for a concrete or timber floor by its natural frequency, one column per frequency, for every storey • ground to foundation (Tables A.3 and A.4) for a basement or a ground floor, as 'mean', 'lower' or 'upper' • foundation to floor (Tables A.5 and A.6) against the ratio of the band to the natural frequency, interpolated in decibels over the logarithm of the ratio, nan where the print has none	vibration.ground_to_floor_transfer_db('concrete', floor_natural_frequency_hz=8.0)[3] # 15.0
point_to_line_transition_distance_m / line_source_correction_db / train_decay_exponent / train_velocity_ratio / LINE_SOURCE_EXPONENT_CORRECTION / RECOMMENDED_DISTANCES_M	function / constant	Annex B and Table 1 of E DIN 45672-3: a train is a line of point sources, and how far a prediction should reach. • R_0 = L² / lambda (Formula (B.1)); 20 n_Korr lg(r / r_0) with n_Korr 0,3 or 0,5 by how the point decay was fitted (Formula (B.2)); the exponent of a train and the piecewise decay of Figure B.1 • the distances of Table 1: 25 m from a surface tram to 200 m from freight on soft ground	vibration.train_decay_exponent(1.0) # 0.7
far_field_velocity_mm_s / geometric_exponent / reference_distance_m / attenuation_coefficient_per_m / material_damping_factor / SOURCE_EXPONENTS / TRAIN_CHAIN_EXPONENT_RANGE / LOOSE_GROUND_DAMPING_RATIO	function / constant	DIN 4150-1:2001-06 Clause 4.2: how far vibration carries through the ground. • far_field_velocity_mm_s(reference_velocity_mm_s, distance_m, *, reference_distance_m, exponent, attenuation_per_m): Formula (2), spreading with the exponent of Figure 1 and damping with alpha = 2π D / lambda, beyond R_1 = a/2 + lambda_R (Formula (1)) • geometric_exponent(*, geometry, character, wave): 0, 0,5, 1 or 1,5; a train decays with 0,3 to 0,5; loose ground has a damping ratio of 0,01 at most in a first estimate	vibration.far_field_velocity_mm_s(0.44, [80.0], reference_distance_m=13.0, exponent=1.0, attenuation_per_m=0.005) # 0.051
soil_building_natural_frequency_hz / soil_building_frequency_guide_hz / foundation_transfer_max / floor_transfer_max / storey_frequency_hz / LOOSE_GROUND_SYSTEM_DAMPING / FOUNDATION_TRANSFER_ABOVE_RESONANCE / FLOOR_DAMPING_RATIO_RANGE / MEDIUM_SOIL_SHEAR_WAVE_SPEED_M_S / STOREY_FORMULA_MIN_STOREYS	function / constant	DIN 4150-1 Clause 4.3: the building on its ground. • Formula (3), the natural frequency of the building as a mass on the spring of the ground, about 15 Hz for one or two storeys, 8 Hz to 12 Hz for two to six and under 8 above six on medium ground (c_s 150 to 200 m/s), two storeys taking the union of the two ranges it is printed in • the most a foundation passes at resonance, 1 / (2 D_0) = 2 for loose ground, and 0,5 above it; the most a floor amplifies, 1 / (2 D_1) = 10 to 25 for concrete; 10 / n Hz for the lowest horizontal mode of n ≥ 5 storeys (Formula (4))	vibration.floor_transfer_max(0.02) # 25.0
blast_peak_velocity_mm_s / impact_peak_velocity_mm_s / fall_energy_kj / BLASTING_RELEVANT_DISTANCE_M	function / constant	DIN 4150-1 Clause 5.1: single events in the far field. • blast_peak_velocity_mm_s(charge_kg, distance_m, *, coefficient_mm_s, charge_exponent, distance_exponent): k (L/L_0)^b (R/R_0)^-m with constants from trial blasts (Formula (5)) • impact_peak_velocity_mm_s(fall_energy_kj, distance_m, *, coefficient_mm_s, distance_exponent): the same with the root of the fall energy G h (Formula (6)); quarry blasting is rarely relevant beyond 1500 m, construction blasting beyond 400 m	vibration.fall_energy_kj(25506.0, drop_height_m=70.0) # 1.79e6
track_excitation_frequency_hz / RAIL_SUPPORT_SPACING_M / VEHICLE_NATURAL_FREQUENCIES_HZ / TRACK_TRANSMITTED_BANDS_HZ / RAIL_INFLUENCE_RANGE_M / MACHINE_FREQUENCY_BANDS_HZ	function / constant	DIN 4150-1 Clauses 5.3 and 5.4: what a track and a machine excite at. • f_A = v_Z / d and its multiples for sleepers 0,6 m to 0,9 m apart; the car body at 1 Hz to 3 Hz and the bogie at 6 Hz to 10 Hz whatever the speed; ballast passes 40 Hz to 80 Hz, a mass-spring system 5 Hz to 20 Hz; rail vibration reaches 80 m • counter-blow hammers 4 Hz to 8 Hz, forging presses 5 Hz to 15 Hz sideways, frame saws 4 Hz to 8 Hz	vibration.track_excitation_frequency_hz(20.0, spacing_m=0.6) # [33.3]
machine_hall_velocity_mm_s / machine_count_correction / MACHINE_COUNT_CORRECTION / MACHINE_COUNT_AXIS	function / constant	DIN 4150-1 Clause 5.4.2, Formula (7) and Figure 3: a hall of similar machines. • machine_hall_velocity_mm_s(reference_velocity_mm_s, machine_count, *, reference_count): chi v_B sqrt(N), measured with N_B of them running • chi is printed only as a nomogram, for N_B of 3, 5, 10, 30, 60 or 100 from 4 to 100 machines, and is here as the curves read off the page at a five-hundredth	vibration.machine_hall_velocity_mm_s(0.44, [60.0], reference_count=3) # 1.0
evaluate_train_passage / TrainPassage	function / dataclass	One train passage reduced the way DIN 45672-2 reduces it (Clauses 5 to 7). • velocity_mm_s [mm/s] as the transducer gives it, fs_hz [Hz], an integer • keyword-only: t2_s (the passage, read off the record), t1_s (Default: 4 s centred on the peak, never longer than T₂), t3_s (Default: the whole record), upper_band_hz (Default: 315; down to 80) • .intervals_s, .interval_rms_mm_s, .peak_velocity_mm_s, .running_rms_max_mm_s, .kbf_max, .event_velocity_mm_s, .event_level_db, .band_centres_hz, .band_interval_levels_db (one row per stretch), .band_max_levels_db, .plot(), .plot_spectrum() • the record goes through the railway band limitation of DIN 45669-1 before anything is read	p = vibration.evaluate_train_passage(v, 2048, t2_s=(6.75, 23.25)) • p.event_velocity_mm_s, p.band_max_levels_db
running_velocity_rms / running_velocity_level / running_acceleration_level	function	Formulae (1) to (3): the running r.m.s. with τ = 125 ms, and its levels. • levels re v₀ = 5·10⁻⁸ m/s and a₀ = 10⁻⁶ m/s² • started from rest: the mean square is 14 % short after 2τ and 2 % after 4τ, the r.m.s. about half that	vibration.running_velocity_level(v, 2048)[-1]
interval_rms / centred_interval	function	Formulae (4) and (5), and the stretch T₁ of Clause 5 a). • interval_rms(values, fs_hz, interval_s=(start, end)): handed the velocity it is Formula (4), handed the running r.m.s. it is Formula (5) • centred_interval(v, fs_hz, duration_s=4): the largest amplitude in the middle, moved rather than cut where the record ends	vibration.interval_rms(v, 2048, interval_s=(8.0, 20.0))
event_velocity / event_velocity_level / combined_event_velocity	function	Formulae (8) to (10): the event value referred to an hour, its level, and an hour of passages. • v_E = ṽ₃ √(T₃ / 3600 s), from interval_rms_mm_s and duration_s • the passages of an hour add in square	vibration.event_velocity(0.1, 36.0) # 0.01
passage_average_velocity / passage_average_level	function	Clause 9: the energy average over repeated passages. • r.m.s. values as the root of the mean square, levels as the level of the mean energy • keyword-only axis: passage_average_level(spectra, axis=0) averages third-octave spectra band by band	vibration.passage_average_level([60, 70]) # 67.40
amplitude_distribution / AmplitudeDistribution	function / dataclass	Formula (11): the amplitude distribution density and its cumulative function (Clause 6.3). • keyword-only bins (Default: 101, equal bins across the range of the stretch) • .edges_mm_s, .density_per_mm_s, .cumulative	vibration.amplitude_distribution(v).cumulative[-1] # 1.0
narrowband_psd / passage_energy_spectral_density / spectral_density_level	function	Formulae (12) to (14), and the level Figure 7 draws. • narrowband_psd(v, fs_hz, resolution_hz=1.25): Welch with a Hanning window and half a block of overlap, as a SpectralDensityResult • passage_energy_spectral_density(psd, duration_s): Formula (13) as printed, G₂ T₂ / 2, a two-sided density • spectral_density_level(psd): 10 lg(G / G₀) with G₀ = (5·10⁻⁸ m/s)²/Hz	vibration.narrowband_psd(v, 2048).nperseg / 2048 # 0.8
third_octaves_from_narrowband / THIRD_OCTAVE_LINES / NARROWBAND_RESOLUTION_HZ	function / constant	Formula (23) with Table 1: a narrow-band spectrum back into third octaves. • each band takes its Table 1 count of lines, the ones nearest its nominal centre on a logarithmic axis: the lines inside the nominal edges wherever the count is what they hold • six lines fall between bands and five are in two, as nominal edges leave them; a band the spectrum does not hold whole is left out • refuses a spectrum not spaced 1,25 Hz, the spacing the counts are written for	c, rms = vibration.third_octaves_from_narrowband(f, psd)
velocity_psd_from_voltage / elastic_insertion_loss / band_sum_level	function	Annex A and Annex B. • Annex A: a density in V²/Hz divided by κ_A² κ_V², keyword-only sensitivity_v_per_mm_s and gain • (B.1) the insertion loss of an elastic element, L₁ − L₂ per band, which is also the difference spectrum of (B.2) • (B.3) the energy sum of the bands	vibration.band_sum_level([60, 60]) # 63.01
VELOCITY_LEVEL_REFERENCE_MM_S / EVENT_REFERENCE_DURATION_S / T1_DURATION_S / PASSAGE_BANDS_HZ	constant	The numbers DIN 45672-2 is built from. • v₀ = 5·10⁻⁸ m/s, here 5e-5 mm/s (Formula (2); the 50 nm/s of note b of ISO 1683:2015 Table 3, 34 dB from its 1 nm/s) • 3600 s, the hour of Formula (8), and 4 s, the recommended T₁ • 4 Hz to 315 Hz, the third-octave range of 7.2	vibration.VELOCITY_LEVEL_REFERENCE_MM_S # 5e-05
poisson_ratio_from_wave_speeds / shear_modulus_from_wave_speed / youngs_modulus_from_wave_speeds	function	DIN 45672-1 Clause 4.5: the ground's constants from its two wave speeds. • Formula (3) ν = (v_p² − 2v_s²) / (2(v_p² − v_s²)) and Formula (5) G = v_s² ρ • E = 2G(1 + ν), not the printed E = v_p² ρ, which is the P-wave modulus; see docs/ERRATA.md • speeds in m/s, keyword-only density_kg_m3	vibration.poisson_ratio_from_wave_speeds(400.0, 180.0) # 0.373
compression_wave_speed / shear_strain_amplitude	function	Formula (1) corrected, and Formula (4). • v_p = √(2G(1 − ν) / (ρ(1 − 2ν))), the continuum; the print is short of the factor 2 • γ̂ = v̂ / v_s, with the velocity amplitude in m/s	vibration.shear_strain_amplitude(2e-4, shear_wave_speed_m_s=180.0)
GROUND_WAVE_SPEED_RANGES_M_S / SHEAR_STRAIN_LINEAR_LIMIT	constant	What Clause 4.5 gives for natural ground. • compression waves 200-2000 m/s and shear waves 10-1000 m/s • 10⁻⁴: the shear strain up to which Figure 1 has the modulus about constant	vibration.SHEAR_STRAIN_LINEAR_LIMIT # 0.0001
fdtd_simulation	function	2D acoustic FDTD wave simulation (staggered grid, leapfrog). • c: sound-speed map [m/s], (ny, nx) array or scalar with shape • dx: grid spacing [m] • duration: physical time to simulate [s] • sources: GaussianPulse | CWSource | SignalSource list • probes: (ix, iy) pressure-probe cells • boundaries: "rigid" | "absorbing" | per-side mapping (name or real impedance [Pa·s/m]) • obstacle_mask: boolean (ny, nx) rigid-cell map / rho / cfl / damping / absorbing_layer_cells / snapshot_every	res = simulation.fdtd_simulation(343, 0.01, 0.02, shape=(200, 300), sources=[simulation.GaussianPulse(ix=60, iy=100, half_width_s=3e-4)], probes=[(200, 100)]) • FDTDResult
FDTDResult	dataclass	FDTD simulation result. • times [s] / pressures [Pa] per probe / probes / probe_positions [m] • dx / dt / shape / size [m] / sources / snapshots / snapshot_times / obstacle_mask • .plot(): probe histories; .plot(kind="snapshot"): pressure field	res.pressures, res.times res.plot()
FDTD2D	class	FDTD stepping engine (frame-by-frame access). • c [m/s] / dx [m] / rho [kg/m³] / cfl / shape • sponge_width / sponge_sides / sponge_reflection / damping • edge_impedance: per-side real impedance [Pa·s/m] / obstacle_mask	sim = simulation.FDTD2D(343, 0.01, shape=(200, 300)) sim.add_source(src); sim.step(); sim.run(400, record_every=10) • sim.p / sim.vx / sim.vy / sim.dt / sim.time / sim.energy() • sim.plot_geometry(probes=...): draw the configured domain before running • sim.add_plane_wave(direction, center=..., width=..., wavelength=...): one-way plane packet initial condition • sim.add_contour_probe(ix0, ix1, iy0, iy1, frequencies=...): on-the-fly p/v_n phasor capture on a closed contour
GaussianPulse	dataclass	Gaussian pulse source for the FDTD solver. • ix / iy: source cell • width [s] / t0 [s] (Default: 4*width) / amplitude [Pa]	GaussianPulse(ix=60, iy=100, half_width_s=3e-4)
PlaneWaveSource	dataclass	Sustained one-way plane wave injected on a line (TF/SF style). • direction: 'down'/'up'/'left'/'right' (travel) • waveform: callable t → p_inc(t) [Pa] (reuse a point source's .value) • offset: line position in cells from the launch edge (place it just inside a sponge) • amplitude (Default: 1.0)	sim.add_source(simulation.PlaneWaveSource('down', simulation.CWSource(0, 0, frequency=1000.0).value, offset=22)) • Transversely plane to machine precision; ~1e-4 residual behind the line
CWSource	dataclass	Continuous sine source with raised-cosine onset for the FDTD solver. • ix / iy: source cell • frequency [Hz] / amplitude [Pa] / ramp_cycles	CWSource(ix=25, iy=25, frequency=170)
SignalSource	dataclass	Arbitrary sampled waveform source for the FDTD solver. • ix / iy: source cell • samples [Pa] / fs [Hz] / amplitude Linearly interpolated onto the simulation time steps	SignalSource(ix=60, iy=100, samples=sig, fs=48000)
ContourProbe	class	On-the-fly DFT of p and v_n on a closed rectangular contour. Created by FDTD2D.add_contour_probe; complex accumulators per point and frequency, so CW runs store no time histories • positions / normals / frequencies / samples • .reset(): restart accumulation once the field is steady • .phasors(frequency): the captured ContourPhasors	probe = sim.add_contour_probe(90, 470, 90, 345, frequencies=[2000.0]) sim.run(steps); probe.reset(); sim.run(window) ph = probe.phasors(2000.0)
ContourPhasors	dataclass	Steady-state p and v_n phasors on a closed contour (exp(+jωt)). • frequency [Hz] / positions (n, 2) [m] / normals (outward) • pressure [Pa] / normal_velocity [m/s] (complex) / segment [m] • .subtract(reference): scattered = total − incident phasors	scattered = total.subtract(reference)
far_field_from_contour	function	2D near-to-far-field transformation (Kirchhoff-Helmholtz integral). • contour: ContourPhasors • angles_deg [deg]: observation directions (cos a, sin a) in grid axes • distance: None (far-field pattern F(a), p → F e^{−jkr}/√r) or a radius [m] for the exact Hankel evaluation • origin: phase-reference point • fluid: Fluid (Default: SIMULATION_AIR, the medium the solver runs in)	F = simulation.far_field_from_contour(ph, np.arange(-180, 180, 2), origin=(xc, yc)) • Complex pattern, one value per angle_deg
elastic_fdtd_simulation	function	2D elastic P-SV FDTD wave simulation (velocity-stress, Virieux staggered grid). • c_p / c_s: wave-speed maps [m/s], (ny, nx) arrays or scalars with shape (c_s = 0 marks fluid cells) • dx: grid spacing [m] / duration [s] / rho: density map [kg/m³] • sources: ExplosionSource | ForceSource list • recording: ElasticRecording (probe cells and fields, snapshot cadence and field) • boundaries: ElasticBoundaries (the four sides and the sponge thickness) • obstacle_mask / cfl / damping	res = simulation.elastic_fdtd_simulation(6320, 3130, 0.001, 5e-5, rho=2700, shape=(300, 600), sources=[simulation.ForceSource(ix=300, iy=0, direction='y', waveform=simulation.GaussianPulse(0, 0, half_width_s=8e-6).value)], boundaries=simulation.ElasticBoundaries({'top': 'free'})) • ElasticFDTDResult
ElasticFDTDResult	dataclass	Elastic FDTD simulation result. • times [s] / signals (n_probes, n_fields, n_steps+1) / probe_fields / probes / probe_positions [m] • dx / dt / shape / size [m] / sources / snapshots / snapshot_times / snapshot_field / obstacle_mask / free_sides • .plot(): probe histories; .plot(kind="snapshot"): recorded field	res.signals, res.times res.plot()
ElasticRecording	dataclass	What an elastic FDTD run records. • probes: (ix, iy) cells (Default: none) • probe_fields: ("p" | "vx" | "vy", ...) (Default: ("vy",)) • snapshot_every steps (Default: None) • snapshot_field (Default: "p")	ElasticRecording(probes=[(300, 0)], snapshot_every=50, snapshot_field='vy')
ElasticBoundaries	dataclass	How the four edges of the elastic domain end. • sides: "rigid" (Default) | "absorbing" | "free" (stress-imaging surface) | per-side mapping • absorbing_layer_cells (Default: 20)	ElasticBoundaries({'top': 'free'}, absorbing_layer_cells=40)
ElasticFDTD2D	class	Elastic P-SV stepping engine (frame-by-frame access). • c_p / c_s [m/s] / dx [m] / rho [kg/m³] / cfl / shape • free_sides: traction-free surfaces (stress imaging) • sponge_width / sponge_sides / sponge_reflection / damping / obstacle_mask	sim = simulation.ElasticFDTD2D(6320, 3130, 0.001, rho=2700, shape=(300, 600), free_sides='top') sim.add_source(src); sim.step(); sim.run(400, record_every=10) • sim.txx / sim.tyy / sim.txy / sim.vx / sim.vy / sim.p / sim.lam / sim.mu / sim.dt / sim.time / sim.energy() • sim.collocated(field): one field interpolated to cell centres
ElasticFDTD2D.from_regions	classmethod	Layered/embedded set-ups from named materials (no manual maps). • shape: (ny, nx) / dx [m] • background: Material or (c_p, c_s, rho) filling the grid • regions: (where, material) pairs painted in order (where: boolean mask or numpy index) • remaining kwargs forwarded to the constructor	sim = ElasticFDTD2D.from_regions((300, 600), 0.001, background=WATER, regions=[(np.s_[150:, :], STEEL)])
Material	dataclass	Isotropic medium as wave speeds and density (frozen). • c_p [m/s] / c_s [m/s] (0 marks a fluid) / rho [kg/m³] • is_fluid: c_s == 0 Must satisfy c_p² ≥ 2 c_s² (non-negative λ)	Material(c_p=5958, c_s=3184.7, rho=7850)
SIMULATION_AIR	Fluid	The air the acoustic solvers run in. 343.0 m/s, 1.2 kg/m³, the AIR Material written as a fluid • the fluid default of far_field_from_contour • a phonometry.fluids.Fluid: pass a computed one, or a water, to transform out of the medium the run actually used	simulation.SIMULATION_AIR.density # 1.2
AIR / WATER / STEEL / ALUMINIUM / CONCRETE	Material	Named media, the three solids read off Bies 5e Table C.1. air 343/0/1.2, water 1480/0/1000, steel 5958/3184.7/7850, aluminium 6450.5/3098.7/2700, concrete 3726.8/2282.2/2400 (c_p/c_s/ρ) • each solid's density is printed and its two speeds follow from the modulus and Poisson ratio beside it	ElasticFDTD2D.from_regions((240, 480), 0.005, background=WATER, regions=[(np.s_[120:, :], STEEL)])
scholte_speed	function	Exact Scholte interface-wave speed of a fluid over an elastic half-space. • fluid: Material with c_s = 0 (or triple) • solid: Material with c_s > 0 Root of the exact characteristic equation (Brekhovskikh & Godin Eq. 4.4.20); non-dispersive, below both the fluid speed and the solid shear speed	scholte_speed(WATER, STEEL) # 1479.6 • v [m/s]
ExplosionSource	dataclass	Isotropic (explosive) stress source for the elastic solver. • ix / iy: source cell • waveform: callable t → injected pressure [Pa] (reuse a point source's .value) • amplitude (Default: 1.0) Pressure-like sign: equal -s(t) increments on both normal stresses	ExplosionSource(ix=250, iy=250, waveform=simulation.GaussianPulse(0, 0, half_width_s=8e-6).value)
ForceSource	dataclass	Directional body-force source for the elastic solver. • ix / iy: staggered velocity node • direction: 'x' | 'y' • waveform: callable t → line force [N/m] / amplitude A vertical force under a free surface reproduces Lamb's problem	ForceSource(ix=300, iy=0, direction='y', amplitude=1e6, waveform=simulation.GaussianPulse(0, 0, half_width_s=8e-6).value)
PhonometryWarning	warning class	Base class for all phonometry warnings. Emitted by every module through the subclass of its own domain, so catching this one catches every library advisory at once	warnings.simplefilter('error', PhonometryWarning)
FilterBankWarning	warning class	Fractional-octave filter-bank advisory. Emitted for filter-bank processing pitfalls	warnings.simplefilter('error', FilterBankWarning)
TonalityWarning	warning class	Tonality advisory. Emitted for biased tonality estimates (e.g. coarse FFT resolution)	warnings.simplefilter('error', TonalityWarning)
STIWarning	warning class	STI/STIPA advisory. Emitted for suspect speech-intelligibility measurements or inputs	warnings.simplefilter('error', STIWarning)
__version__	str	Package version string. (no parameters)	phonometry.__version__ # '4.0.0rc1'
.plot()	method	One-line canonical figure on every result object (soft matplotlib dependency). Available on ZwickerLoudness, MooreGlasbergLoudness, MooreGlasbergTimeVaryingLoudness, EcmaLoudness, EcmaTonality, EcmaRoughness, PsychoacousticAnnoyanceResult, FluctuationStrengthResult, ProgramLoudnessResult, KWeightingResponse, STIResult, SIIResult, SIIProcedure, StandardSpeechSpectrum, NCResult, RCResult, AgeThresholdResult, NiptsResult, HtlanResult, ImpulseProminenceResult, ImpulsiveSoundResult, SelDistribution, DirectivityFactor, RandomIncidenceSensitivity, DiffuseFieldSensitivity, AdjustmentValue, FreeFieldCorrection, CorrectionUncertaintyBudget, CorrectionUncertaintyVerification, MultipleShockResult, ImpulseResponseResult, DecayCurve, RoomAcousticsResult, ReverberationResult, ReverberationModelResult, DynamicStiffnessResult, MobilityResult, TransferStiffnessResult, BandAveragedStiffness, LevelDifferenceCheck, OutputMassCheck, EffectiveBlockingMass, DrivingPointStiffnessResult, DrivingPointUncertainty, VibrationSoundPowerResult, StructureBornePowerResult, InstalledSourceResult, WeightedRatingResult, ImpactRatingResult, FacadeInsulationResult, LabAirborneInsulationResult, LabImpactInsulationResult, SoundPowerResult, SoundEnergyResult, ReverberationSoundPowerResult, ReverberationSoundEnergyResult, InSituSoundPowerResult, InDuctSoundPowerResult, HighFrequencySoundPowerResult, SoundPowerIntensityResult, DiscretePointIntensityResult, PrecisionSoundPowerResult, PrecisionIntensityResult, IntensityResult, UncertaintyResult, AbsorptionRatingResult, ScatteringResult, DiffusionResult, DiffusionSpectrum, InsituAbsorptionResult, WeightingResponse, WeightedSpectrum, Signal and DailyVibrationExposure. • ax: existing Axes, or None to build a fresh figure (Default: None) • returns the Matplotlib Axes (an array of Axes for multi-panel figures); never calls plt.show() • needs matplotlib (pip install phonometry[plot])	res.plot() decay_curve(ir, fs).plot()

Notes

• zero_phase=True (in OctaveFilterBank.filter and spectrogram) filters forward-backward (sosfiltfilt): no group delay, doubled effective attenuation, offline analysis only. Incompatible with stateful=True. The passband also narrows, lowering the measured broadband band level by ~0.2 to 0.3 dB per band (a pure in-band tone is unaffected); prefer forward filtering when the absolute band SPL must match single-pass conventions, and reserve zero-phase for when the temporal envelope matters (e.g. reverberation decay).
• mode='peak' includes the filter's onset transient; a tone that starts abruptly can overshoot by ~1 dB. See Calibration and dBFS.
• octave_filter() caches filter bank designs internally (32 entries), so repeated calls with the same parameters skip the design phase. For explicit control use OctaveFilterBank.
• The 3.1 aliases are gone, as their notices said they would be in 4.0: octavefilter, getansifrequencies, normalizedfreq, calculate_sensitivity, the bare coverage_factor and expanded_uncertainty of ISO 12999-1, the OCTAVE_BANDS_HZ, THIRD_OCTAVE_BANDS_HZ and BASE_PLATE_BANDS_HZ constants, BAND_CENTRES, ExposureWarning, and the sample_rate, humidity and room_volume keywords. Use octave_filter, nominal_frequencies, normalized_frequencies, sensitivity, insulation_coverage_factor, insulation_expanded_uncertainty, OCTAVE_BANDS, THIRD_OCTAVE_BANDS, BASE_PLATE_BANDS, phonometry.speech.sii.BAND_CENTERS, OccupationalExposureWarning, fs, relative_humidity_percent and volume.