emission.sound_power_reverberation

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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, with the Sabine absorption area and the speed of sound c in m/s (ISO 3741:2010 clause 9.1.4, Eq. 20):

L_{p} (ST) = 10 lo g_{10} [\frac{1}{N _{M}} i \sum 1 0^{0.1 L_{p i}}] (Eq. 16)

A = \frac{55.26}{c} \frac{V}{T _{60}}

c = 20.05 273 + θ

L_{W} = L_{p} (ST) + 10 lo g_{10} \frac{A}{A _{0}} + 4.34 \frac{A}{S} + 10 lo g_{10} (1 + \frac{S c}{8 V f}) + C_{1} + C_{2} - 6 (Eq. 20)

$10 lo g_{10} (1 + S c / (8 V f))$ 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 %), per clause 9.1.4:

C_{1} = - 10 lo g_{10} \frac{p _{s}}{p _{s 0}} + 5 lo g_{10} \frac{273.15 + θ}{314}

C_{2} = - 10 lo g_{10} \frac{p _{s}}{p _{s 0}} + 15 lo g_{10} \frac{273.15 + θ}{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):

L_{W} = L_{W} (RSS) + (L_{p} (ST) - L_{p} (RSS) + C_{2}) (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.

A noise burst or a transient emission is described by the sound energy level $L_{J} = 10 lo g_{10} (J / J_{0})$ , $J_{0} = 1$ pJ (clause 3.18), and clause 9.2 determines it by the same two methods with the single event time-integrated sound pressure level $L_{E}$ (clause 3.4) in place of the time-averaged $L_{p}$ : the $N_{e}$ events at each position are reduced to the level of one event (Eq. 22 or Eq. 23), each position is corrected for its background by $K_{1 i}$ (Eq. 25, 26) as in 9.1.2, the positions are energy-averaged (Eq. 27), and the room enters through the same bracket as Eq. (20) or the same reference source as Eq. (21):

L_{J} = \overline{L_{E} (ST)} + [10 lo g_{10} \frac{A}{A _{0}} + 4.34 \frac{A}{S} + 10 lo g_{10} (1 + \frac{S c}{8 V f}) + C_{1} + C_{2} - 6] (Eq. 30)

L_{J} = L_{W} (RSS) + (\overline{L_{E} (ST)} - \overline{L_{p} (RSS)}) + C_{2} (Eq. 31)

For a source steady over the whole interval $T$ , clause 3.4 NOTE 1 gives $L_{E} = L_{p, T} + 10 lo g_{10} (T / T_{0})$ , $T_{0} = 1$ s, and so $L_{J} = L_{W} + 10 lo g_{10} (T / T_{0})$ . Annex F sums the one-third-octave levels into octave bands (Eq. F.1, F.4) and A-weights them (Eq. F.2, F.5) alike for the two quantities.

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octave_band_levels

octave_band_levels(
    levels: np.ndarray,
    frequencies: np.ndarray,
) -> tuple[np.ndarray, np.ndarray]

Octave-band levels from one-third-octave band levels (ISO 3741 Annex F).

The level in the $i$ -th octave band, $1 \leq i \leq 8$ for the mid-band frequencies 63 Hz to 8 kHz, is the energy sum of the three one-third-octave bands $k = 3 i - 2$ to $3 i$ of Table F.1 that make it up, for sound power levels (Eq. F.1) and sound energy levels (Eq. F.4) alike:

L_{J i} = 10 lo g_{10} k = 3 i - 2 \sum 3 i 1 0^{0.1 L_{J k}}

Every octave the input touches must be supplied whole: Table F.1 numbers the one-third-octave bands from $k = 1$ at 50 Hz, so the 63 Hz octave is the 50, 63 and 80 Hz thirds and the 8 kHz octave the 6,3, 8 and 10 kHz thirds, and a band whose triplet is incomplete cannot be summed.

Parameters

Name	Description
`levels`	Band levels in decibels, with the bands on the last axis (`(NB,)`, or `(..., NB)` for several spectra at once).
`frequencies`	The `NB` nominal one-third-octave mid-band frequencies of `levels`, in hertz, from 50 Hz to 10 kHz.

Returns: (octave mid-band frequencies, octave-band levels), the frequencies ascending and the levels with the octaves on the last axis.

Raises

Exception	When
ValueError	for a frequency outside Table F.1, a repeated frequency, an octave whose three thirds are not all present, or levels that do not carry one value per frequency.

ReverberationSoundEnergyResult

ReverberationSoundEnergyResult(
    frequencies: np.ndarray | None,
    sound_energy_level: np.ndarray,
    mean_event_level: np.ndarray,
    absorption_area: np.ndarray,
    waterhouse_correction: np.ndarray,
    background_correction: np.ndarray,
    c1: float,
    c2: float,
    speed_of_sound: float,
    sound_energy_level_a: float,
    method: str,
    events: int | None,
    integration_time: float | None,
)

Result of an ISO 3741:2010 reverberation-room sound energy level determination (clause 9.2).

sound_energy_level is the per-band LJ (Eq. 30 direct method, Eq. 31 comparison method), under reference meteorological conditions as both equations state it. mean_event_level is the mean corrected single event time-integrated level in the room $\overline{L_{E} (ST)}$ (Eq. 27). absorption_area, waterhouse_correction, c1, c2, speed_of_sound and background_correction are what they are in ReverberationSoundPowerResult, the background correction being the per-band shift of the mean level after each position was corrected by its own K1i (Eq. 25/26). sound_energy_level_a is the A-weighted total LJA (Annex F Eq. F.5), computed only when frequencies are supplied (NaN for several bands without them; equal to LJ for a single band). method is 'direct' or 'comparison'. events is the number of single sound emission events $N_{e}$ the levels were reduced from, or None when the caller supplied the mean single event level of one event; integration_time is the interval $T$ of the single event levels, in seconds, or None when no background correction needed it.

ReverberationSoundEnergyResult.plot()

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

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

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

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 $10 lo g_{10} (1 + S c / (8 V f))$ ; 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_energy_comparison

sound_energy_comparison(
    levels: np.ndarray,
    levels_ref: np.ndarray,
    lw_ref: np.ndarray,
    *,
    frequencies: np.ndarray | None = None,
    events: int | None = None,
    background_levels: np.ndarray | None = None,
    integration_time: float | None = None,
    background_levels_ref: np.ndarray | None = None,
    temperature: float = 23.0,
    static_pressure: float = 101.325,
) -> ReverberationSoundEnergyResult

Sound energy level in a reverberation room, comparison method (ISO 3741:2010 clause 9.2.5).

A reference sound source of known per-band sound power lw_ref runs steadily at the same microphone positions as the source under test, whose single event levels levels take any of the forms sound_energy_reverberation accepts. The sound energy level in each band follows Eq. (31):

L_{J} = L_{W} (RSS) + (\overline{L_{E} (ST)} - \overline{L_{p} (RSS)}) + C_{2}

where $\overline{L_{E} (ST)}$ is the mean corrected single event level of the source under test (Eq. 27), $\overline{L_{p} (RSS)}$ the mean corrected time-averaged level of the reference source (Eq. 17) and C2 the radiation-impedance correction. The room terms and C1 cancel between the two sources exactly as in sound_power_comparison. The source under test is background-corrected as in sound_energy_reverberation (its background compared as an exposure over integration_time); the reference source, being steady, by the time-averaged correction of 9.1.2.

Parameters

Name	Description
`levels`	Single event levels of the source under test, in decibels.
`levels_ref`	Mean room SPL per band (1D) or `(NM, NB)` per-position time-averaged levels of the reference sound source, in decibels.
`lw_ref`	Known sound power level `LW(RSS)` per band, in decibels, under the meteorological conditions of the test.
`frequencies`	Band mid-frequencies (Hz) for the `K1` criterion and the A-weighted total.
`events`	The number of events `Ne` one measurement encompasses (Eq. 23); `None` when `levels` is per event or already the mean of one event.
`background_levels`	Time-averaged background levels for the `K1` correction of `levels` (per position, or a single spectrum).
`integration_time`	The interval `T` of the single event levels, in seconds; required with `background_levels`.
`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: ReverberationSoundEnergyResult (method='comparison').

Raises

Exception	When
ValueError	for a malformed or non-finite level array, a non-physical climate, a background without its `integration_time` or without `frequencies`, or mismatched band counts.

sound_energy_reverberation

sound_energy_reverberation(
    levels: np.ndarray,
    t60: float | np.ndarray,
    volume: float,
    surface_area: float,
    frequencies: np.ndarray,
    *,
    events: int | None = None,
    background_levels: np.ndarray | None = None,
    integration_time: float | None = None,
    temperature: float = 23.0,
    static_pressure: float = 101.325,
) -> ReverberationSoundEnergyResult

Sound energy level in a reverberation room, direct method (ISO 3741:2010 clause 9.2.4).

levels holds the single event time-integrated sound pressure levels $L_{E i (ST)}^{'}$ measured through a period that encompasses the whole of the event, its decay included (clause 8.5.1; a moving microphone is not permitted for non-repetitive impulsive noise): a 1D per-band spectrum already averaged over the room, a 2D (NM, NB) array of one event’s level at each position, a 3D (Ne, NM, NB) array of the $N_{e}$ events measured one at a time (reduced by Eq. 22), or a 1D/2D level of one measurement encompassing events successive events (reduced by Eq. 23). Each position is corrected for its background by $K_{1 i}$ (Eq. 25/26, the frequency-dependent criterion of 9.1.2), the positions are energy-averaged (Eq. 27) and the sound energy level in each band follows Eq. (30):

L_{J} = \overline{L_{E} (ST)} + [10 lo g_{10} \frac{A}{A _{0}} + 4.34 \frac{A}{S} + 10 lo g_{10} (1 + \frac{S c}{8 V f}) + C_{1} + C_{2} - 6]

with every term of the bracket exactly as in sound_power_reverberation (Eq. 20), so the level is stated under the reference meteorological conditions of clause 4. The background is the time-averaged level the standard has measured over the same integration time $T$ as the events (clause 9.2.2), and it is compared as its exposure over that $T$ , $L_{p i (B)} + 10 lo g_{10} (T / T_{0})$ (clause 3.4 NOTE 1), so that the energies Eq. (25) subtracts share one reference; integration_time is therefore required with background_levels.

Parameters

Name	Description
`levels`	Single event levels, in decibels, in one of the four forms above.
`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 band mid-frequencies, Hz (required: the Waterhouse term and the `K1` criterion need them).
`events`	The number of events `Ne` one measurement encompasses (Eq. 23); `None` when `levels` is per event or already the mean of one event.
`background_levels`	Time-averaged background levels for `K1`: per-position `(NM, NB)` (or a single `(NB,)` spectrum used at every position) with per-position `levels`, applied per position before the energy average; with 1D `levels` a single `K1` from the averaged spectra approximates the per-position procedure.
`integration_time`	The interval `T` of the single event levels, in seconds; required with `background_levels`.
`temperature`	Air temperature `theta` in the room, in degrees Celsius.
`static_pressure`	Static pressure `ps` in the room, in kilopascals.

Returns: ReverberationSoundEnergyResult (method='direct').

Raises

Exception	When
ValueError	for a malformed or non-finite level array, a non-physical room or climate, a background without its `integration_time`, or mismatched band counts.

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):

L_{W} = L_{W} (RSS) + (L_{p} (ST) - L_{p} (RSS) + C_{2})

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: float | 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):

L_{W} = L_{p} (ST) + 10 lo g_{10} \frac{A}{A _{0}} + 4.34 \frac{A}{S} + 10 lo g_{10} (1 + \frac{S c}{8 V f}) + C_{1} + C_{2} - 6

with the Sabine equivalent absorption area $A = (55.26/ c) (V / T_{60})$ and the speed of sound $c = 20.05 273 + θ$ . The Waterhouse term $10 lo g_{10} (1 + S c / (8 V f))$ 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.

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