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

$$
L_p(\text{ST}) = 10 \log_{10}\!\left[ \frac{1}{N_\mathrm{M}} \sum_i 10^{0.1 L_{pi}} \right] \tag{Eq. 16}
$$

$$
A = \frac{55.26}{c} \, \frac{V}{T_{60}}
$$

$$
c = 20.05 \sqrt{273 + \theta}
$$

$$
L_W = L_p(\text{ST}) + 10 \log_{10}\frac{A}{A_0} + 4.34 \frac{A}{S} + 10 \log_{10}\!\left( 1 + \frac{S c}{8 V f} \right) + C_1 + C_2 - 6 \tag{Eq. 20}
$$

$10 \log_{10}(1 + Sc/(8Vf))$ 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:

$$
C_1 = -10 \log_{10}\frac{p_\mathrm{s}}{p_{\mathrm{s}0}} + 5 \log_{10}\frac{273.15 + \theta}{314}
$$

$$
C_2 = -10 \log_{10}\frac{p_\mathrm{s}}{p_{\mathrm{s}0}} + 15 \log_{10}\frac{273.15 + \theta}{296}
$$

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):

$$
L_W = L_W(\text{RSS}) + \left( L_p(\text{ST}) - L_p(\text{RSS}) + C_2 \right) \tag{Eq. 21}
$$

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** $L_J = 10 \log_{10}(J/J_0)$, $J_0 = 1$ 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 $N_\mathrm{e}$ 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 $K_{1i}$ (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):

$$
L_J = \overline{L_E(\text{ST})} + \left[ 10 \log_{10}\frac{A}{A_0} + 4.34 \frac{A}{S} + 10 \log_{10}\!\left( 1 + \frac{S c}{8 V f} \right) + C_1 + C_2 - 6 \right] \tag{Eq. 30}
$$

$$
L_J = L_W(\text{RSS}) + \left( \overline{L_E(\text{ST})} - \overline{L_p(\text{RSS})} \right) + C_2 \tag{Eq. 31}
$$

For a source steady over the whole interval $T$, clause 3.4 NOTE 1
gives $L_E = L_{p,T} + 10 \log_{10}(T/T_0)$, $T_0 = 1$ s, and
so $L_J = L_W + 10 \log_{10}(T/T_0)$. 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.

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

## octave_band_levels

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

$$
L_{Ji} = 10 \log_{10} \sum_{k=3i-2}^{3i} 10^{0.1 L_{Jk}}
$$

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. |

## reverberation_background_correction

```python
reverberation_background_correction(
    levels: ArrayLike,
    background_levels: ArrayLike,
    frequencies: ArrayLike,
) -> NDArray[np.float64]
```

Background-noise correction $K_1$, ISO 3741:2010 Equation (14).

$K_1 = -10 \lg (1 - 10^{-0,1 \Delta L_p})$, the decibels to take off
a band level measured with the background in it. The qualification of
clause 9.1.2 is frequency dependent: a margin of 15 dB or more needs no
correction at all, and below the lower criterion, 6 dB for the bands at or
under 200 Hz and at or over 6,3 kHz and 10 dB between them, the correction
is held at the criterion value and the corrected level is an upper bound.

Other standards reach for this one by name rather than repeat it:
ISO 11957:1996 asks for a correction "in accordance with ISO 3741" four
times over, and [`phonometry.noise_control.cabin_insulation`](/phonometry/reference/api/noise_control/cabin-insulation/) calls
this.

**Parameters**

| Name | Description |
| :--- | :--- |
| `levels` | Band levels measured with the background present, in decibels. |
| `background_levels` | Background levels in the same bands, in decibels. |
| `frequencies` | Nominal band centre frequencies, in hertz. |

**Returns:** $K_1$ per band, in decibels, to be subtracted from `levels`.

**Raises**

| Exception | When |
| :--- | :--- |
| ValueError | For inputs that do not match band for band, that are not finite, or a band centre that is not strictly positive. |

## ReverberationSoundEnergyResult

```python
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 $\overline{L_E(\text{ST})}$
(Eq. 27). `absorption_area`, `waterhouse_correction`, `c1`, `c2`,
`speed_of_sound` and `background_correction` are what they are in
[`ReverberationSoundPowerResult`](/phonometry/reference/api/power/sound-power-reverberation/#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 $N_\mathrm{e}$ 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()

```python
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

```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 $10 \log_{10}(1 + Sc/(8Vf))$; 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_c`, `relative_humidity_percent`, `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

```python
sound_energy_comparison(
    levels: np.ndarray,
    levels_ref: np.ndarray,
    lw_ref: np.ndarray | ReferenceSourceCalibration,
    *,
    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_c: float = 23.0,
    static_pressure_kpa: 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`](/phonometry/reference/api/power/sound-power-reverberation/#sound_energy_reverberation) accepts. The sound energy level in each
band follows Eq. (31):

$$
L_J = L_W(\text{RSS}) + \left( \overline{L_E(\text{ST})} - \overline{L_p(\text{RSS})} \right) + C_2
$$

where $\overline{L_E(\text{ST})}$ is the mean corrected single event
level of the source under test (Eq. 27), $\overline{L_p(\text{RSS})}$
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`](/phonometry/reference/api/power/sound-power-reverberation/#sound_power_comparison). The
source under test is background-corrected as in
[`sound_energy_reverberation`](/phonometry/reference/api/power/sound-power-reverberation/#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 (Eq. 31), or the [`ReferenceSourceCalibration`](/phonometry/reference/api/power/reference-sound-source/#referencesourcecalibration) of ISO 6926, read in the one-third octave bands at `frequencies` and carried from the reference conditions to those of the test by its own `C2`. |
| `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_c` | Air temperature `theta` in the room, in degrees Celsius. |
| `static_pressure_kpa` | Static pressure `ps` in the room, in kilopascals. |

**Returns:** [`ReverberationSoundEnergyResult`](/phonometry/reference/api/power/sound-power-reverberation/#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

```python
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_c: float = 23.0,
    static_pressure_kpa: 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
$L'_{Ei(\mathrm{ST})}$ 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
$N_\mathrm{e}$ 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
$K_{1i}$ (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):

$$
L_J = \overline{L_E(\text{ST})} + \left[ 10 \log_{10}\frac{A}{A_0} + 4.34 \frac{A}{S} + 10 \log_{10}\!\left( 1 + \frac{S c}{8 V f} \right) + C_1 + C_2 - 6 \right]
$$

with every term of the bracket exactly as in [`sound_power_reverberation`](/phonometry/reference/api/power/sound-power-reverberation/#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
$T$, $L_{pi(\mathrm{B})} + 10 \log_{10}(T/T_0)$ (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_c` | Air temperature `theta` in the room, in degrees Celsius. |
| `static_pressure_kpa` | Static pressure `ps` in the room, in kilopascals. |

**Returns:** [`ReverberationSoundEnergyResult`](/phonometry/reference/api/power/sound-power-reverberation/#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

```python
sound_power_comparison(
    levels: np.ndarray,
    levels_ref: np.ndarray,
    lw_ref: np.ndarray | ReferenceSourceCalibration,
    *,
    frequencies: np.ndarray | None = None,
    background_levels: np.ndarray | None = None,
    background_levels_ref: np.ndarray | None = None,
    temperature_c: float = 23.0,
    static_pressure_kpa: 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):

$$
L_W = L_W(\text{RSS}) + \left( L_p(\text{ST}) - L_p(\text{RSS}) + C_2 \right)
$$

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, under the meteorological conditions of the test (Eq. 21), or the [`ReferenceSourceCalibration`](/phonometry/reference/api/power/reference-sound-source/#referencesourcecalibration) of ISO 6926, read in the one-third octave bands at `frequencies` and carried from the reference conditions to those of the test by its own `C2`. |
| `frequencies` | Band mid-frequencies (Hz) for the A-weighted total; required with a calibration. |
| `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_c` | Air temperature `theta` in the room, in degrees Celsius. |
| `static_pressure_kpa` | 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: float | np.ndarray,
    volume: float,
    surface_area: float,
    frequencies: np.ndarray,
    *,
    background_levels: np.ndarray | None = None,
    temperature_c: float = 23.0,
    static_pressure_kpa: 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):

$$
L_W = L_p(\text{ST}) + 10 \log_{10}\frac{A}{A_0} + 4.34 \frac{A}{S} + 10 \log_{10}\!\left( 1 + \frac{S c}{8 V f} \right) + C_1 + C_2 - 6
$$

with the Sabine equivalent absorption area
$A = (55.26/c)(V/T_{60})$ and the speed of sound
$c = 20.05 \sqrt{273 + \theta}$. The Waterhouse term
$10 \log_{10}(1 + Sc/(8Vf))$ 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_c` | Air temperature `theta` in the room, in degrees Celsius. |
| `static_pressure_kpa` | Static pressure `ps` in the room, in kilopascals. |

**Returns:** [`ReverberationSoundPowerResult`](/phonometry/reference/api/power/sound-power-reverberation/#reverberationsoundpowerresult).