environment.propagation.noise_reducing_devices

Single-number ratings of noise reducing devices (EN 1793, EN 16272).

A barrier beside a road is not judged band by band. It is judged by two numbers, and both are the same operation on a spectrum nobody measures on site: the normalised traffic noise spectrum of EN 1793-3:1997, eighteen one-third octave bands from 100 Hz to 5 kHz carrying relative A-weighted levels $L_i$ that stand for what a road sounds like at the roadside.

A barrier beside a railway is judged the same way and by a different spectrum. EN 16272-3-1:2012 prints the normalised railway noise spectrum over the same eighteen bands, and its Clauses 5 and 6 are the two formulas below with that table in place of the other one: rolling noise puts its weight higher up, so the railway spectrum is flat within one decibel from 1,25 kHz to 2,5 kHz where the road one has already begun to fall away. The railway parts carry no category ladder; their annexes are guidance notes, and a rating there is the number and nothing more.

• EN 1793-1:2012 rates absorption. What matters to the neighbour is the energy the device sends back across the road, so the rating is what is not absorbed, in decibels (Clause 5):

  $$D{L}_{\alpha }=-10\lg \left|1-\frac{{\sum }_{i=1}^{18}{\alpha }_{\mathrm{S}i}10^{0.1L_i}}{{\sum }_{i=1}^{18}10^{0.1L_i}}\right|$$

  A measured ${\alpha }_{\mathrm{S}}$ can exceed one band by band, which can push the weighted ratio past 1 and leave the logarithm without an argument. The clause says so and fixes it: the ratio is limited to 0,99.

• EN 1793-2:2012 rates airborne insulation with the same weighting (Clause 5.2), on the transmitted energy rather than the absorbed:

  $$D{L}_R=-10\lg \left|\frac{{\sum }_{i=1}^{18}10^{0.1L_i}10^{-0.1R_i}}{{\sum }_{i=1}^{18}10^{0.1L_i}}\right|$$

Both are reported rounded to the nearest integer (EN 1793-1 Clause 6.1, EN 1793-2 Clause 7.1), and both have a normative category ladder in their Annex A: A1 to A5 for absorption, B1 to B4 for insulation, with A0 and B0 reserved for “not determined”. The categories are read off the reported integer, which is why the ladders have no gaps between their steps.

The two ratings answer different questions and are not comparable. A device can be a perfect reflector and still keep the noise out (high $D{L}_R$, low $D{L}_{\alpha }$); a device can be highly absorptive and let sound through (the other way round). The declaration carries both.

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

Constant (tuple).

ABSORPTION_CATEGORIES = (('A1', -2147483648, 3), ('A2', 4, 7), ('A3', 8, 11), ('A4', 12, 15), ('A5', 16, 2147483648))

Constant (float).

ABSORPTION_RATIO_LIMIT = 0.99

airborne_insulation_rating(
    sound_reduction_index_db: ArrayLike,
    *,
    spectrum: str = 'road',
) -> RoadDeviceRating

DL_R, the single-number rating of airborne sound insulation.

EN 1793-2:2012 Clause 5.2 for a road device, EN 16272-3-1:2012 Clause 6 for a railway one, on the same weighting as the absorption rating above.

Parameters

Returns: The rating, its reported integer and, for a road device, its Annex A category.

Raises

Constant (tuple).

INSULATION_CATEGORIES = (('B1', -2147483648, 14), ('B2', 15, 24), ('B3', 25, 34), ('B4', 35, 2147483648))

Constant (tuple).

NORMALISED_RAILWAY_NOISE_SPECTRUM_DB = (-27.0, -25.0, -23.0, -21.0, -19.0, -17.0, -15.0, -13.0, -12.0, -11.0, -10.0, -9.0, -9.0, -9.0, -9.0, -10.0, -13.0, -17.0)

Constant (tuple).

NORMALISED_TRAFFIC_NOISE_SPECTRUM_DB = (-20.0, -20.0, -18.0, -16.0, -15.0, -14.0, -13.0, -12.0, -11.0, -9.0, -8.0, -9.0, -10.0, -11.0, -13.0, -15.0, -16.0, -18.0)

RoadDeviceRating(
    rating: float,
    reported: int,
    category: str | None,
    quantity: str,
    spectrum: str,
    bands_hz: NDArray[np.float64],
    values: NDArray[np.float64],
    weights: NDArray[np.float64],
)

One single-number rating of a road traffic noise reducing device.

Attributes

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

Plot the per-band input against the spectrum that weights it.

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

Raised when a rating is computed on data the standard bounds.

sound_absorption_rating(
    absorption_coefficients: ArrayLike,
    *,
    spectrum: str = 'road',
) -> RoadDeviceRating

DLα, the single-number rating of sound absorption.

EN 1793-1:2012 Clause 5 for a road device, EN 16272-3-1:2012 Clause 5 for a railway one: the same formula over the same eighteen bands, with the spectrum of the matching part in the weights. Only the road parts print a category ladder, so a railway rating carries none.

Parameters

Returns: The rating, its reported integer and, for a road device, its Annex A category.

Raises

Warns

Constant (mapping).

SPECTRA = {'road': (-20.0, -20.0, -18.0, -16.0, -15.0, -14.0, -13.0, -12.0, -11.0, -9.0, -8.0, -9.0, -10.0, -11.0, -13.0, -15.0, -16.0, -18.0), 'railway': (-27.0, -25.0, -23.0, -21.0, -19.0, -17.0, -15.0, -13.0, -12.0, -11.0, -10.0, -9.0, -9.0, -9.0, -9.0, -10.0, -13.0, -17.0)}

Constant (tuple).

TRAFFIC_NOISE_BANDS_HZ = (100.0, 125.0, 160.0, 200.0, 250.0, 315.0, 400.0, 500.0, 630.0, 800.0, 1000.0, 1250.0, 1600.0, 2000.0, 2500.0, 3150.0, 4000.0, 5000.0)