building.measurement.rainfall_sound

Sound of rain on roofs, roof windows and rooflights, measured in the laboratory with artificial rain (ISO 10140-1:2021 Annex K, ISO 10140-5:2021 Annexes H and I).

Rain is an impact source that falls on the roof rather than a noise that comes through it, so ISO 10140-1 measures it as impact sound: a tank with a perforated base drops water on the specimen at a controlled rate, and the sound radiated into the test room below is reported as a sound intensity level $L_I$, the sound power per unit area of the specimen referred to $10^{-12}$ W/m² (K.1). Per unit area, because only part of a large roof is wetted and the power scales with the area the rain actually excites.

The rain. Real rain is classed by rate, drop size and fall velocity (Table K.1, after IEC 60721-2-2:1988, RAINFALL_CLASSIFICATION). The laboratory reproduces two of the classes at their upper limits, “since larger drops produce most of the sound generated”: heavy rain, 40 mm/h of 5 mm drops at 7 m/s, which is mandatory and the one products are compared with, and intense rain, 15 mm/h of 2 mm drops at 4 m/s (ISO 10140-5:2021 Table H.1, ARTIFICIAL_RAIN). The generator is checked by its rainfall rate, which has to stay within 2 mm/h of the nominal value (verify_rain_generator, rainfall_rate).

The level. From the room-averaged sound pressure level $L_{\mathrm{pr}}$, the reverberation time $T$ and the volume $V$ of the test room and the area $S_{\mathrm{e}}$ the rain excites,

(Formula (K.1), $T_0=1$ s, $V_0=1$ m³, $S_0=1$ m²), which is the diffuse-field sound power $L_p+10{\log }_{10}(A/4)$ with the Sabine area $A=0.16V/T$ written out and divided by the excited area. With three positions of the generator on a large specimen the three levels are added energetically and $S_{\mathrm{e}}$ is three times the perforated area of the tank (K.4.2). The alternative of K.4.3 measures the intensity directly, $L_I=L_{I\mathrm{m}}+10{\log }_{10}(S_{\mathrm{m}}/S_{\mathrm{e}})$ (Formula (K.4)). The 18 bands 100 Hz to 5 000 Hz combine into the A-weighted level $L_{I\mathrm{A}}=10{\log }_{10}\sum 10^{0.1(L_{Ij}+C_j)}$ (Formula (K.2)) with the $C_j$ of Table K.2 (RAINFALL_A_WEIGHTING), and three bands into an octave by Formula (K.3).

The reference specimen. For comparison between laboratories, the levels are normalized with the result for a 6 mm glass pane of 1,25 m by 1,5 m under heavy rain (K.6, ISO 10140-5:2021 Annex I): its measured level is corrected to the reference loss factor of Table I.1, $L_{I,\mathrm{m},\mathrm{ref}}=L_{I,\mathrm{ref}}+10{\log }_{10}(\eta /{\eta }_{\mathrm{ref}})$ with $\eta =2.2/(f{T}_{\mathrm{s}})$ (Formulas (I.1) and (I.2)), and the difference from the reference level of the same table is the correction $\Delta L_{I\mathrm{c}}=L_{I,\mathrm{m},\mathrm{ref}}-L_{I\mathrm{c},\mathrm{ref}}$ (Formula (I.3)) that every later specimen subtracts, $L_{I\mathrm{norm}}=L_I-\Delta L_{I\mathrm{c}}$ (Formula (K.5)).

Citations are to ISO 10140-1:2021 and ISO 10140-5:2021. Both tables of the reference specimen and the rain types are printed identically in ISO 10140-5:2010/Amd 1:2014, where they first appeared.

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

Constant (mapping).

ARTIFICIAL_RAIN = {'intense': ArtificialRain(rainfall_rate_mm_h=15.0, median_drop_diameter_mm=2.0, fall_velocity_m_s=4.0, hole_diameter_mm=(0.3, 0.5), holes_per_m2=25.0, fall_height_m=1.0, rainfall_rate_tolerance_mm_h=2.0, drop_diameter_tolerance_mm=0.5, fall_velocity_tolerance_m_s=1.0), 'heavy': ArtificialRain(rainfall_rate_mm_h=40.0, median_drop_diameter_mm=5.0, fall_velocity_m_s=7.0, hole_diameter_mm=(1.0, 1.0), holes_per_m2=60.0, fall_height_m=3.5, rainfall_rate_tolerance_mm_h=2.0, drop_diameter_tolerance_mm=0.5, fall_velocity_tolerance_m_s=1.0)}

ArtificialRain(
    rainfall_rate_mm_h: float,
    median_drop_diameter_mm: float,
    fall_velocity_m_s: float,
    hole_diameter_mm: tuple[float, float],
    holes_per_m2: float,
    fall_height_m: float,
    *,
    rainfall_rate_tolerance_mm_h: float = 2.0,
    drop_diameter_tolerance_mm: float = 0.5,
    fall_velocity_tolerance_m_s: float = 1.0,
)

One type of artificial rain and the tank that makes it (ISO 10140-5 Annex H).

Attributes

Constant (mapping).

RAINFALL_A_WEIGHTING = {100.0: -19.1, 125.0: -16.1, 160.0: -13.4, 200.0: -10.9, 250.0: -8.6, 315.0: -6.6, 400.0: -4.8, 500.0: -3.2, 630.0: -1.9, 800.0: -0.8, 1000.0: 0.0, 1250.0: 0.6, 1600.0: 1.0, 2000.0: 1.2, 2500.0: 1.3, 3150.0: 1.2, 4000.0: 1.0, 5000.0: 0.5}

Constant (mapping).

RAINFALL_CLASSIFICATION = {'moderate': RainfallType(rainfall_rate_mm_h=(None, 4.0), drop_diameter_mm=(0.5, 1.0), fall_velocity_m_s=(1.0, 2.0)), 'intense': RainfallType(rainfall_rate_mm_h=(None, 15.0), drop_diameter_mm=(1.0, 2.0), fall_velocity_m_s=(2.0, 4.0)), 'heavy': RainfallType(rainfall_rate_mm_h=(None, 40.0), drop_diameter_mm=(2.0, 5.0), fall_velocity_m_s=(5.0, 7.0)), 'cloudburst': RainfallType(rainfall_rate_mm_h=(100.0, None), drop_diameter_mm=(3.0, None), fall_velocity_m_s=(6.0, None))}

rainfall_rate(
    collected_volume_litres: float,
    collection_area_m2: float,
    duration_s: float,
) -> float

Rainfall rate from the water collected over an area and a time (H.2.3).

The periodic check of a tank generator is “collecting the water over a given area over a precisely measured time period”: the rate is the depth of that water, one litre per square metre being one millimetre, scaled to one hour (the definition under Table H.1).

Parameters

Returns: The rainfall rate, in mm/h.

Raises

rainfall_reference_correction(
    l_i_ref_db: ArrayLike,
    structural_reverberation_time_s: ArrayLike,
    frequencies_hz: ArrayLike | None = None,
) -> RainfallReferenceCorrection

Correction $\Delta L_{I\mathrm{c}}$ of a laboratory (ISO 10140-5 I.2).

The small reference specimen is a single 6 mm glass pane of 1,25 m by 1,5 m, mounted as a window pane of ISO 10140-1:2021 Annex D and wetted by heavy rain centred on it. Its structural reverberation time gives its loss factor, $\eta =2.2/(f{T}_{\mathrm{s}})$ (Formula (I.1)), and its measured intensity level is brought to the reference loss factor of Table I.1, $L_{I,\mathrm{m},\mathrm{ref}}=L_{I,\mathrm{ref}}+10{\log }_{10}(\eta /{\eta }_{\mathrm{ref}})$ (Formula (I.2)): a pane mounted more lossily radiates less, and the correction removes that part of the difference, which belongs to the mounting and not to the laboratory’s rain. What remains, $\Delta L_{I\mathrm{c}}=L_{I,\mathrm{m},\mathrm{ref}}-L_{I\mathrm{c},\mathrm{ref}}$ (Formula (I.3)), is subtracted from every specimen the laboratory measures (ISO 10140-1:2021 Formula (K.5)). No reference specimen is defined for large specimens (I.3).

$f$ in Formula (I.1) is taken as the band centre frequency given.

Parameters

Returns: A RainfallReferenceCorrection.

Raises

Constant (mapping).

RAINFALL_REFERENCE_INTENSITY_DB = {100.0: 45.0, 125.0: 45.0, 160.0: 46.0, 200.0: 46.0, 250.0: 47.0, 315.0: 47.0, 400.0: 47.0, 500.0: 47.0, 630.0: 47.0, 800.0: 46.0, 1000.0: 44.0, 1250.0: 42.0, 1600.0: 43.0, 2000.0: 46.0, 2500.0: 51.0, 3150.0: 50.0, 4000.0: 46.0, 5000.0: 44.0}

Constant (mapping).

RAINFALL_REFERENCE_LOSS_FACTOR_DB = {100.0: -10.0, 125.0: -11.0, 160.0: -11.0, 200.0: -12.0, 250.0: -13.0, 315.0: -13.0, 400.0: -14.0, 500.0: -14.0, 630.0: -15.0, 800.0: -15.0, 1000.0: -16.0, 1250.0: -17.0, 1600.0: -17.0, 2000.0: -18.0, 2500.0: -18.0, 3150.0: -19.0, 4000.0: -19.0, 5000.0: -20.0}

rainfall_sound(
    l_pr_db: ArrayLike,
    reverberation_time_s: ArrayLike,
    frequencies_hz: ArrayLike,
    *,
    volume_m3: float,
    excited_area_m2: float,
    background_db: ArrayLike | None = None,
    reference_correction: RainfallReferenceCorrection | ArrayLike | None = None,
) -> RainfallSoundResult

Sound intensity level of a specimen under artificial rain (K.4.2).

While the rain falls steadily on the specimen, the room-averaged sound pressure level $L_{\mathrm{pr}}$ and the reverberation time $T$ of the test room are measured to ISO 10140-4, and each band gives

(Formula (K.1)). A small specimen (a roof window or rooflight, about 1,25 m by 1,5 m) is wetted from one position and $S_{\mathrm{e}}$ is its area; a large one (10 m² to 20 m²) from three, whose levels are added energetically, and $S_{\mathrm{e}}$ is three times the perforated area of the tank. The 18 bands 100 Hz to 5 000 Hz give the A-weighted level $L_{I\mathrm{A}}$ of Formula (K.2).

With the correction of the laboratory’s reference specimen (rainfall_reference_correction), the levels are also normalized, $L_{I\mathrm{norm}}=L_I-\Delta L_{I\mathrm{c}}$ (Formula (K.5)), for comparison between laboratories.

Parameters

Returns: A RainfallSoundResult.

Raises

rainfall_sound_from_intensity(
    l_im_db: ArrayLike,
    frequencies_hz: ArrayLike,
    *,
    measuring_area_m2: float,
    excited_area_m2: float,
    reference_correction: RainfallReferenceCorrection | ArrayLike | None = None,
) -> RainfallSoundResult

Sound intensity level of a specimen under rain, measured directly (K.4.3).

The alternative of K.4.3 measures the intensity with a probe over a surface $S_{\mathrm{m}}$ enclosing the specimen (ISO 15186-1, in any room meeting its field indicator and background requirements), and refers it to the excited area, $L_I=L_{I\mathrm{m}}+10{\log }_{10}(S_{\mathrm{m}}/S_{\mathrm{e}})$ (Formula (K.4)). The A-weighted level, the octaves and the normalization then follow as in K.4.2.

Parameters

Returns: A RainfallSoundResult with method="intensity".

Raises

RainfallReferenceCorrection(
    frequencies_hz: np.ndarray,
    l_i_ref_db: np.ndarray,
    structural_reverberation_time_s: np.ndarray,
    loss_factor: np.ndarray,
    reference_loss_factor: np.ndarray,
    l_i_m_ref_db: np.ndarray,
    l_ic_ref_db: np.ndarray,
    correction_db: np.ndarray,
)

The normalization correction from the reference glass pane (Annex I).

Attributes

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

Plot the corrected reference level against Table I.1.

The gap between the two curves is the correction every specimen of the laboratory is normalized by. Requires matplotlib (pip install phonometry[plot]); returns the Axes.

RainfallSoundResult(
    frequencies_hz: np.ndarray,
    l_i_db: np.ndarray,
    l_ia_db: float | None,
    method: str,
    correction_db: np.ndarray | None = None,
    l_i_norm_db: np.ndarray | None = None,
    l_ia_norm_db: float | None = None,
)

Sound intensity level radiated by a specimen under rain (Annex K).

Attributes

RainfallSoundResult.octave_bands(
    *,
    normalized: bool = False,
) -> tuple[np.ndarray, np.ndarray]

(octave centres in Hz, LIoct in dB) by Formula (K.3).

$L_{I\mathrm{oct}}=10{\log }_{10}{\sum }_{j=1}^{3}10^{0.1L_{I,j}}$ over the three one-third-octave bands of each octave present.

Parameters

Raises

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

Plot the sound intensity level per band, normalized when available.

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

RainfallSoundResult.sound_power_levels(
    specimen_area_m2: float,
) -> np.ndarray

Sound power level radiated by the whole specimen, per band.

$L_W=L_I+10{\log }_{10}(S/S_0)$ (the NOTE to Formula (K.2)), with $S$ the area of the whole specimen.

Parameters

Returns: $L_W$ per band, in dB re 1 pW.

Raises

RainfallType(
    rainfall_rate_mm_h: tuple[float | None, float | None],
    drop_diameter_mm: tuple[float | None, float | None],
    fall_velocity_m_s: tuple[float | None, float | None],
)

One class of natural rain (ISO 10140-1:2021 Table K.1).

Each quantity is a (lower, upper) pair; None is an open end: the table prints the three lighter classes as “up to” a rate and cloudburst as “greater than” every quantity.

Attributes

RainGeneratorVerification(
    rain_type: str,
    rainfall_rate_mm_h: float,
    drop_diameters_mm: np.ndarray | None,
    fall_velocities_m_s: np.ndarray | None,
)

Whether an artificial rain generator makes the rain it should (H.1, H.2.3).

The windows are the rows of Table H.1 the rain type selects, so the shares and the verdicts are read from the measured samples and are not fields: a verification cannot be built to pass a rain the table fails.

Attributes

property

Share of the measured drops within the diameter window, or None.

property

Whether at least half of the drops are within it (“should”), or None.

property

The row of ARTIFICIAL_RAIN the generator was verified against.

property

Whether every judged requirement holds.

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

Plot each measured quantity against its tolerance window.

Every quantity is drawn as its deviation from the nominal value in units of its tolerance, so the three share one axis and the window is -1 to 1. Requires matplotlib (pip install phonometry[plot]); returns the Axes.

property

Measured minus nominal rate, in mm/h.

property

Whether the rate is within the tolerance (“shall”), bounds included.

property

Whether at least half of the drops fall within it (“should”), or None.

property

Share of the measured drops within the velocity window, or None.

verify_rain_generator(
    rainfall_rate_mm_h: float,
    *,
    rain_type: str = 'heavy',
    drop_diameters_mm: ArrayLike | None = None,
    fall_velocities_m_s: ArrayLike | None = None,
) -> RainGeneratorVerification

Does the rain generator make the rain of Table H.1 (ISO 10140-5:2021)?

H.1 sets three tolerances on the generated rain: the rainfall rate “shall be within ±2 mm/h” of the nominal rate, and half of the drops “should be within ±0,5 mm” of the volume median drop diameter and “within ±1 m/s” of the fall velocity. A tank built to Table H.2 needs only the rate checked (H.2.3), by collecting the water (rainfall_rate); another generator needs the drops measured as well, and the drop criteria are judged when their samples are given. The three windows include their bounds: a rate exactly 2 mm/h from the nominal one passes, also when rainfall_rate returns it a rounding error beyond.

Parameters

Returns: A RainGeneratorVerification.

Raises