Source: https://jmrplens.github.io/phonometry/reference/api/power/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): ```text 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 %): ```text 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): ```text 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 ```python 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() ```python 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() ```python 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`](/phonometry/reference/api/building/insulation/#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 ```python 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): ```text 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`](/phonometry/reference/api/power/sound-power-reverberation/#reverberationsoundpowerresult) (`method='comparison'`). ## sound_power_reverberation ```python 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): ```text 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`](/phonometry/reference/api/power/sound-power-reverberation/#reverberationsoundpowerresult).