emission.sound_power_anechoic

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Sound power level of a noise source in an anechoic or hemi-anechoic room, from sound pressure measurements over an enveloping surface: ISO 3745:2012 (precision, accuracy grade 1).

This is the precision sibling of ISO 3744:2010 (engineering) and ISO 3746:2010 (survey), and the path from the surface-averaged pressure to the sound power level is the same one. What sets it apart is the room. In a qualified (hemi-)free field there is no reflected energy to correct for, so the environmental correction $K_{2}$ disappears altogether; in its place the standard asks for more of everything else. The background correction is evaluated at every microphone position and every band against a frequency-dependent criterion (clause 9.4.2), the microphone array is a fixed 40-position equal-area set tabulated for the sphere (Annex D) and the hemisphere (Annex E), and three meteorological corrections refer the determination to the reference atmosphere (clause 9.5):

K_{1 i} = - 10 lo g_{10} (1 - 1 0^{- 0.1Δ L_{p i}}) (Eq. 11)

\overline{L_{p}} = 10 lo g_{10} [\frac{1}{N _{M}} i \sum 1 0^{0.1 (L_{p i}^{'} - K_{1 i})}] (Eq. 12)

L_{W} = \overline{L_{p}} + 10 lo g_{10} \frac{S}{S _{0}} + C_{1} + C_{2} + C_{3} (Eq. 14/15)

The measurement surface is a full sphere $S = 4 π r^{2}$ in an anechoic room (Eq. 14) or a hemisphere $S = 2 π r^{2}$ over the reflecting plane of a hemi-anechoic room (Eq. 15), and each tabulated position carries an equal share of it; unequal partial areas $S_{i}$ are averaged by Eq. 13 instead. The A-weighted total is combined with the ISO 3744 Annex E band corrections (Annex C, Eq. C.1) and the expanded uncertainty $U = k σ_{R 0}^{2} + σ_{omc}^{2}$ (Eq. 24/25) takes its reproducibility standard deviation from Table 3 (anechoic) or Table 2 (hemi-anechoic).

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meteorological_corrections

meteorological_corrections(
    temperature: float = 23.0,
    static_pressure: float = 101.325,
    *,
    air_absorption_coefficient: float | np.ndarray | None = None,
    radius: float = 1.0,
) -> MeteorologicalCorrection

Meteorological corrections C1, C2, C3 (ISO 3745:2012 Eq. 14 block).

Using the measured static pressure $p_{s}$ (kPa) and air temperature $θ$ (deg C) form:

C_{1} = - 10 lo g_{10} \frac{p _{s}}{p _{s, 0}} + 5 lo g_{10} \frac{273 + θ}{θ _{0}}, θ_{0} = 314 K

C_{2} = - 10 lo g_{10} \frac{p _{s}}{p _{s, 0}} + 15 lo g_{10} \frac{273 + θ}{θ _{1}}, θ_{1} = 296 K

C_{3} = A_{0} (1.0053 - 0.0012 A_{0})^{1.6}, A_{0} = α (f) r

$p_{s, 0} = 101.325$ kPa. This is the $p_{s}$ / $θ$ form of C1 (not the characteristic-impedance form), chosen because it needs only the measured $p_{s}$ and $θ$ and is consistent with C2. At the reference conditions (23 deg C, 101.325 kPa) $C_{2} = 0$ exactly while $C_{1} = 5 lo g_{10} (296/314) = - 0.128$ dB. C3 requires the atmospheric attenuation coefficient $α (f)$ from ISO 9613-1 (not computed here); without it $C_{3} = 0$ .

Parameters

Name	Description
`temperature`	Air temperature `theta` at the test, in degrees C.
`static_pressure`	Static pressure `ps` at the test, in kilopascals.
`air_absorption_coefficient`	`a(f)` (dB/m), scalar or per band, for C3; `None` leaves $C_{3} = 0$ .
`radius`	Measurement radius `r` (m), used only in $A_{0} = α (f) r$ .

Returns: MeteorologicalCorrection.

MeteorologicalCorrection

MeteorologicalCorrection(c1: float, c2: float, c3: float | np.ndarray)

Meteorological corrections C1, C2, C3 (ISO 3745:2012 Eq. 14 block).

c1 is the reference-quantity (impedance) correction and c2 the radiation-impedance correction, both scalars in decibels; c3 is the air-absorption correction (scalar, or per band when the attenuation coefficient a(f) is supplied per band). All three are added to $\overline{L_{p}} + 10 lo g_{10} (S / S_{0})$ to obtain LW.

precision_background_correction

precision_background_correction(
    source_levels: np.ndarray,
    background_levels: np.ndarray,
    frequencies: np.ndarray,
) -> np.ndarray

Per-position background correction K1i (ISO 3745:2012 Eq. 11).

$K_{1 i} = - 10 lo g_{10} (1 - 1 0^{- 0.1Δ L_{p i}})$ with $Δ L_{p i} = L_{p i (ST)}^{'} - L_{p i (B)}$ evaluated at each microphone position i and band. Above the upper criterion ( $Δ L_{p i} \geq 15$ dB) the background is negligible and $K_{1 i} = 0$ . The lower criterion is frequency dependent: 10 dB for one-third-octave mid-bands 250 Hz to 5000 Hz and 6 dB for bands $\leq 200$ Hz and $\geq 6300$ Hz. Below it, $K_{1 i}$ is clamped to its value at the criterion (0.46 dB and 1.26 dB respectively), a SoundPowerWarning is emitted and those band results are upper bounds (clause 9.4.2).

Parameters

Name	Description
`source_levels`	`L'pi(ST)` per position and band, in decibels; shape `(NM, NB)` (or `(NB,)` for one position).
`background_levels`	`Lpi(B)` in the same shape (or a single spectrum broadcast to every position).
`frequencies`	`(NB,)` nominal mid-band frequencies (Hz), selecting the per-band lower criterion.

Returns: K1i per position and band, in decibels, matching the broadcast shape of the inputs.

precision_positions

precision_positions(
    surface: PrecisionSurface,
    *,
    radius: float | None = None,
    array: PrecisionArray = 'general',
    count: int = 40,
) -> np.ndarray

Normative ISO 3745:2012 microphone coordinates, scaled by radius.

For a 'sphere' (anechoic room) the coordinates come from Annex D Table D.1; for a 'hemisphere' (hemi-anechoic room) from Annex E Table E.1 (array='general') or Table E.2 (array='broadband', an omnidirectional broadband source). Positions 1-20 are the primary array; the full 40 add the mirror set (positions 21-40), used when the band-SPL spread exceeds NM/2 (clause 9.3). Each row is a unit vector (self-checked) scaled to metres by radius.

Parameters

Name	Description
`surface`	`'sphere'` or `'hemisphere'`.
`radius`	Measurement radius `r`, in metres.
`array`	`'general'` (Table E.1) or `'broadband'` (Table E.2); ignored for a sphere (only Table D.1 exists).
`count`	`20` (primary array) or `40` (full array).

Returns: (count, 3) microphone coordinates, in metres.

precision_uncertainty

precision_uncertainty(
    sigma_r0: float | np.ndarray,
    sigma_omc: float = 0.0,
    coverage_factor: float = 2.0,
) -> float | np.ndarray

Expanded uncertainty $U = k σ_{tot}$ (ISO 3745:2012).

ISO 3745:2012 Eq. 24/25: $σ_{tot} = σ_{R 0}^{2} + σ_{omc}^{2}$ and $U = k σ_{tot}$ , with $k = 2$ (95 %, two-sided) or $k = 1.6$ (95 %, one-sided, when comparing to a limit).

Parameters

Name	Description
`sigma_r0`	Reproducibility standard deviation (Tables 2/3), dB.
`sigma_omc`	Operating/mounting standard deviation `sigma_omc`, dB.
`coverage_factor`	`k` (typically 2 or 1.6).

Returns: U in decibels, scalar or per band matching sigma_r0.

PrecisionSoundPowerResult

PrecisionSoundPowerResult(
    frequencies: np.ndarray | None,
    sound_power_level: np.ndarray,
    surface_pressure_level: np.ndarray,
    mean_pressure_level: np.ndarray,
    background_correction: np.ndarray,
    c1: float,
    c2: float,
    c3: np.ndarray,
    directivity_index: np.ndarray,
    non_uniformity_index: np.ndarray,
    surface_area: float,
    surface: str,
    sound_power_level_a: float,
    uncertainty: float,
    uncertainty_bands: np.ndarray,
    coverage_factor: float,
)

Result of an ISO 3745:2012 (precision) sound power determination.

sound_power_level is the per-band $L_{W} = \overline{L_{p}} + 10 lo g_{10} (S / S_{0}) + C_{1} + C_{2} + C_{3}$ (Eq. 14/15). surface_pressure_level is the surface time- averaged level Lp_bar after the per-position background correction (Eq. 12/13); mean_pressure_level the same energy average of the raw (uncorrected) position levels. background_correction is the per-position per-band K1i (Eq. 11), shape (NM, NB). c1/c2/c3 are the meteorological corrections (Eq. 14). directivity_index is $D I_{i} = L_{p i} - \overline{L_{p}}$ per position and band (Eq. 21); non_uniformity_index the per-band VIr sample standard deviation about the arithmetic mean (Eq. 22). uncertainty is the A-weighted expanded uncertainty $U = k σ_{R 0}^{2} + σ_{omc}^{2}$ (Eq. 24/25) and uncertainty_bands the per-band value (NaN without frequencies). sound_power_level_a is the A-weighted total LWA (Eq. C.1).

PrecisionSoundPowerResult.plot()

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

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

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

PrecisionSoundPowerResult.report()

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

Render an ISO 3745:2012 precision sound-power fiche to a PDF.

Writes the same one-page sound-power test sheet as SoundPowerResult.report, with the standard-basis line naming the precision method in an anechoic or hemi-anechoic room (ISO 3745:2012, accuracy grade 1) and the measurement-basis strip stating the applied meteorological corrections C1/C2/C3 instead of the ISO 3744 K1/K2. The per-band table shows the surface time-averaged level Lp and the band sound-power level LW; verbose adds the energy-averaged level Lp'.

Parameters

Name	Description
`path`	Destination path of the PDF file.
`metadata`	Optional `ReportMetadata` supplying the header and footer identity and, via `requirement`, a declared A-weighted sound-power limit (lower is better).
`engine`	Rendering back end; only `"reportlab"` is supported.
`verbose`	When `True` the per-band table adds the energy-averaged level `Lp'`.
`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_anechoic

sound_power_anechoic(
    levels_positions: np.ndarray,
    surface: PrecisionSurface,
    *,
    radius: float | None = None,
    background_levels: np.ndarray | None = None,
    frequencies: np.ndarray | None = None,
    areas: np.ndarray | None = None,
    temperature: float = 23.0,
    static_pressure: float = 101.325,
    air_absorption_coefficient: float | np.ndarray | None = None,
    sigma_omc: float = 0.0,
    coverage_factor: float = 2.0,
) -> PrecisionSoundPowerResult

Sound power level in an (hemi-)anechoic room (ISO 3745:2012, precision).

levels_positions is an (NM, NB) array of time-averaged position levels $L_{p i (ST)}^{'}$ (one row per microphone, one column per band). Each position is background-corrected by $K_{1 i}$ (Eq. 11, from background_levels and frequencies), the corrected levels are surface-averaged (equal-area Eq. 12, or area-weighted Eq. 13 when areas are given) and combined with the surface area and the meteorological corrections:

L_{W} = 10 lo g_{10} [\frac{1}{N _{M}} i \sum 1 0^{0.1 (L_{p i}^{'} - K_{1 i})}] + 10 lo g_{10} \frac{S}{S _{0}} + C_{1} + C_{2} + C_{3}

$S = 4 π r^{2}$ for a 'sphere' (anechoic, Eq. 14) or $2 π r^{2}$ for a 'hemisphere' (hemi-anechoic, Eq. 15). There is no ISO 3744 K2 environmental term. The reproducibility sigma_R0 is taken from Table 3 (sphere/anechoic) or Table 2 (hemisphere/hemi-anechoic).

Parameters

Name	Description
`levels_positions`	`(NM, NB)` position levels, in decibels.
`surface`	`'sphere'` or `'hemisphere'`.
`radius`	Measurement radius `r`, in metres.
`background_levels`	`(NM, NB)` (or single-spectrum) background levels for `K1i`; requires `frequencies`.
`frequencies`	`(NB,)` nominal mid-band frequencies (Hz), for the K1 criterion, the A-weighted total and the per-band uncertainty.
`areas`	`(NM,)` partial areas `Si` for the area-weighted average (Eq. 13); omit for the equal-area average (Eq. 12).
`temperature`	Air temperature `theta` (deg C), for C1/C2.
`static_pressure`	Static pressure `ps` (kPa), for C1/C2.
`air_absorption_coefficient`	`a(f)` (dB/m) for C3, scalar or per band; `None` leaves $C_{3} = 0$ .
`sigma_omc`	Operating/mounting standard deviation, dB.
`coverage_factor`	`k` (2 two-sided, 1.6 one-sided).

Returns: PrecisionSoundPowerResult.

Creado y mantenido por José Manuel Requena Plens ORCID Todos los proyectos