emission.sound_power_reverberation

Sound power level of a noise source measured in a reverberation test room: ISO 3741:2010 (precision method, accuracy grade 1).

The source is placed in a hard-walled reverberation room whose reverberant field is sampled by microphones. Two methods are provided.

The direct method derives the sound power from the mean corrected room sound pressure level Lp(ST) and the equivalent absorption area A of the room (ISO 3741:2010 clause 9.1.4, Eq. 20):

Lp(ST) = 10*lg( (1/NM) * sum_i 10^(0,1*Lpi) )                     (Eq. 16)
A      = (55,26/c) * (V/T60)          (Sabine)                    (clause 9.1.4)
c      = 20,05 * sqrt(273 + theta)    speed of sound, m/s
LW = Lp(ST) + 10*lg(A/A0) + 4,34*(A/S) + 10*lg(1 + S*c/(8*V*f))
            + C1 + C2 - 6                                         (Eq. 20)

10*lg(1 + S*c/(8*V*f)) is the Waterhouse boundary correction (energy stored near the room boundaries); it vanishes as the frequency grows. C1 (Eq. 20, reference-quantity correction) and C2 (radiation-impedance correction) carry the result to the reference meteorological conditions of clause 4 (23,0 C, 101,325 kPa, 50 %):

C1 = -10*lg(ps/ps0) + 5*lg((273,15+theta)/314)                   (clause 9.1.4)
C2 = -10*lg(ps/ps0) + 15*lg((273,15+theta)/296)

The comparison method replaces the absorption-area terms by a reference sound source (RSS) of known sound power LW(RSS) measured at the same positions (ISO 3741:2010 clause 9.1.5, Eq. 21):

LW = LW(RSS) + ( Lp(ST) - Lp(RSS) + C2 )                         (Eq. 21)

Both methods cover the one-third-octave bands from 100 Hz to 10 kHz (clause 8.1). Octave-band, A-weighted and total levels follow ISO 3741 Annex F, which reuses the ISO 3744 Annex E A-weighting band corrections.

Auto-generated from the source docstrings by scripts/generate_api_docs.py (make api-docs). Do not edit by hand.

ReverberationSoundPowerResult

ReverberationSoundPowerResult(
    frequencies: np.ndarray | None,
    sound_power_level: np.ndarray,
    mean_pressure_level: np.ndarray,
    absorption_area: np.ndarray,
    waterhouse_correction: np.ndarray,
    background_correction: np.ndarray,
    c1: float,
    c2: float,
    speed_of_sound: float,
    sound_power_level_a: float,
    method: str,
)

Result of an ISO 3741:2010 reverberation-room sound power determination.

sound_power_level is the per-band LW (Eq. 20 direct method, Eq. 21 comparison method). mean_pressure_level is the mean corrected room level Lp(ST) (Eq. 16). For the direct method absorption_area is the Sabine equivalent absorption area A per band and waterhouse_correction the boundary term 10*lg(1 + S*c/(8*V*f)); both are NaN for the comparison method. background_correction is the effective per-band background correction K1: with per-position input each position is corrected by its own K1i (Eq. 14/15) before the energy average (Eq. 16), and the reported value is the resulting per-band shift of the mean level (zero when no background is supplied). c1 and c2 are the reference-quantity and radiation-impedance corrections (c1 is NaN for the comparison method, which uses only c2). speed_of_sound is c at the test temperature. sound_power_level_a is the A-weighted total LWA (Annex F Eq. F.2), computed only when frequencies are supplied (NaN for several bands without them; equal to LW for a single band). method is 'direct' or 'comparison'.

ReverberationSoundPowerResult.plot()

ReverberationSoundPowerResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Plot the LW spectrum with the A-weighted total annotated.

Requires matplotlib (pip install phonometry[plot]); returns the Axes.

ReverberationSoundPowerResult.report()

ReverberationSoundPowerResult.report(
    path: str,
    *,
    metadata: ReportMetadata | None = None,
    engine: str = 'reportlab',
    verbose: bool = False,
    language: str = 'en',
) -> str

Render an ISO 3741 reverberation-room sound-power determination fiche.

Writes a one-page sound-power test sheet: the standard-basis line naming the reverberation-room method (the direct method using the room equivalent absorption area, or the comparison method using a reference sound source) and the precision accuracy grade (ISO 3741:2010, grade 1), an optional metadata header (client, noise source, test environment, instrumentation, climate, date), a per-band table (nominal octave/ one-third-octave frequency, the mean room sound-pressure level Lp and the band sound-power level LW), the sound-power spectrum LW(f) with a nominal band axis, the boxed A-weighted sound power level LWA (dB re 1 pW) with the total LW and the determination method, an optional verdict row against a declared limit, and a measurement-basis strip stating the correction model (Eq. 20 direct or Eq. 21 comparison), the applied meteorological corrections C1/C2 and the speed of sound.

Parameters

Name	Description
path	Destination path of the PDF file.
metadata	Optional ReportMetadata supplying the header (client, specimen the noise source, test_room the reverberation test room, instrumentation, temperature, relative_humidity, pressure, test_date), the footer identity (laboratory, operator, report_id, notes) and, via requirement, a declared A-weighted sound-power limit the fiche checks the result against (lower is better).
engine	Rendering back end; only "reportlab" is supported.
verbose	When True the per-band table adds the background correction K1 and, for the direct method, the equivalent absorption area A and the Waterhouse boundary correction Cw.
language	Fiche language: "en" (default) or "es".

Returns: The written path as a str.

Raises

Exception	When
ValueError	If engine is not "reportlab" or language is unknown.
ImportError	If reportlab (or, for the figure, matplotlib) is not installed (pip install phonometry[report]).

sound_power_comparison

sound_power_comparison(
    levels: np.ndarray,
    levels_ref: np.ndarray,
    lw_ref: np.ndarray,
    *,
    frequencies: np.ndarray | None = None,
    background_levels: np.ndarray | None = None,
    background_levels_ref: np.ndarray | None = None,
    temperature: float = 23.0,
    static_pressure: float = 101.325,
) -> ReverberationSoundPowerResult

Sound power level in a reverberation room, comparison method (ISO 3741).

A reference sound source of known per-band sound power lw_ref is measured at the same microphone positions as the source under test. The sound power level in each band follows Eq. (21):

LW = LW(RSS) + ( Lp(ST) - Lp(RSS) + C2 )

where Lp(ST) and Lp(RSS) are the mean room levels (Eq. 16/17) of the test source and the reference source and C2 is the radiation-impedance correction. The absorption-area, Waterhouse and C1 terms cancel between the two sources, so the room absorption need not be known.

Parameters

Name	Description
levels	Mean room SPL per band (1D) or (NM, NB) per-position levels of the source under test, in decibels.
levels_ref	Same, for the reference sound source, in decibels.
lw_ref	Known sound power level LW(RSS) per band, in decibels.
frequencies	Band mid-frequencies (Hz) for the A-weighted total.
background_levels	Background levels for the K1 correction of levels (per position, or a single spectrum; applied per position per Eq. 14/15 before the Eq. 16 average when levels is 2D).
background_levels_ref	Background levels matching levels_ref.
temperature	Air temperature theta in the room, in degrees Celsius.
static_pressure	Static pressure ps in the room, in kilopascals.

Returns: ReverberationSoundPowerResult (method='comparison').

sound_power_reverberation

sound_power_reverberation(
    levels: np.ndarray,
    t60: np.ndarray,
    volume: float,
    surface_area: float,
    frequencies: np.ndarray,
    *,
    background_levels: np.ndarray | None = None,
    temperature: float = 23.0,
    static_pressure: float = 101.325,
) -> ReverberationSoundPowerResult

Sound power level in a reverberation room, direct method (ISO 3741:2010).

levels is either a 1D per-band spectrum of the mean room sound pressure level or a 2D (NM, NB) array (one row per microphone position, one column per band) that is energy-averaged over positions (Eq. 16). The sound power level in each band follows Eq. (20):

LW = Lp(ST) + 10*lg(A/A0) + 4,34*(A/S) + 10*lg(1 + S*c/(8*V*f))
            + C1 + C2 - 6

with the Sabine equivalent absorption area A = (55,26/c)*(V/T60) and the speed of sound c = 20,05*sqrt(273 + theta). The Waterhouse term 10*lg(1 + S*c/(8*V*f)) needs the band mid-frequencies, so frequencies is required. C1 and C2 carry the result to the reference meteorological conditions (clause 4).

Parameters

Name	Description
levels	Mean room SPL per band (1D) or (NM, NB) per-position levels, in decibels.
t60	Reverberation time T60 per band, in seconds (scalar or one value per band).
volume	Reverberation-room volume V, in cubic metres.
surface_area	Total room surface area S, in square metres.
frequencies	One-third-octave (or octave) band mid-frequencies, Hz.
background_levels	Background levels for the K1 correction: per-position (NM, NB) (or a single (NB,) spectrum used at every position) with per-position levels, applied per position (Eq. 14/15) before the energy average (Eq. 16). With 1D pre-averaged levels a single K1 from the averaged spectra approximates the per-position procedure of clause 9.1.2.
temperature	Air temperature theta in the room, in degrees Celsius.
static_pressure	Static pressure ps in the room, in kilopascals.

Returns: ReverberationSoundPowerResult.