aircraft.aircraft_noise

Aircraft noise certification: Effective Perceived Noise Level (ICAO Annex 16).

The EPNL is the noise-certification metric for transport-category aircraft. It is built from a half-second spectral time history (24 one-third-octave bands, 50 Hz-10 kHz) in five steps, implementing ICAO Annex 16 Vol. I, Appendix 2 (the analytic formulation):

• perceived_noisiness — per-band perceived noisiness n (noys), the analytic piecewise noy law with the Table A2-3 constants.
• perceived_noise_level — PNL = 40 + (10/lg2)·lg N from the total noisiness N = 0.85·n_max + 0.15·Σn.
• tone_correction — the tone-correction factor C (the slope / “encircling” method) that penalises spectral irregularities.
• effective_perceived_noise_level — the end-to-end metric: per-record PNLT = PNL + C, the maximum PNLTM, the 10 dB-down integration limits and the duration correction, giving EPNL = PNLTM + D.

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

effective_perceived_noise_level

effective_perceived_noise_level(
    spectra: NDArray[np.float64] | list[list[float]],
    dt: float | NDArray[np.float64] | list[float] = 0.5,
    *,
    reference_time: float = 10.0,
    procedure: str = 'aeroplane',
) -> EPNLResult

Effective Perceived Noise Level from a spectral time history (ICAO Annex 16).

Each record (row) is a 24-band one-third-octave spectrum sampled every dt seconds. The per-record PNL and tone correction C give PNLT = PNL + C; the maximum PNLTM and the duration correction over the 10 dB-down window give EPNL = PNLTM + D.

Parameters

Name	Description
spectra	Spectral time history, shape (K, 24), in dB.
dt	Per-record duration, in s (scalar or per record, default 0.5).
reference_time	Normalising time T0, in s (default 10).
procedure	Tone-correction procedure of App. 2 §4.3.1 Step 1: "aeroplane" (default) starts the slope analysis at the 80 Hz band (band 3), "helicopter" (helicopters and tilt-rotors) at the 50 Hz band (band 1), so rotor tones in the 50-80 Hz bands are not missed.

Returns: An EPNLResult.

Raises

Exception	When
ValueError	If the input is not a (K, 24) finite array, or procedure is not "aeroplane" or "helicopter".

epnl_from_pnlt

epnl_from_pnlt(
    pnlt: NDArray[np.float64] | list[float],
    dt: float | NDArray[np.float64] | list[float] = 0.5,
    *,
    reference_time: float = 10.0,
    tone_corrections: NDArray[np.float64] | list[float] | None = None,
) -> tuple[float, float, int, int]

EPNL from a tone-corrected perceived-noise-level time history (App. 2 §4.5-4.6).

EPNL = 10·lg( Σ_{kF..kL} 10^{PNLT(k)/10}·Δt(k) ) − 10·lg(T0) with the 10 dB-down integration limits about the maximum PNLTM. The exact −10·lg(T0) form is used rather than the Annex’s rounded constant 13 for uniform 0.5 s records (difference 0.0103 dB); the ETM Table 4-4 integrated reference reproduces the exact form to five decimals.

When tone_corrections is given, the bandsharing adjustment ΔB (App. 2 §4.4.2/4.4.3, ETM GM/AMC A2 4.4.2) is applied: if the tone correction at the PNLTM record is below the average of the records within one second of it (five records for the uniform 0.5 s cadence), ΔB is that shortfall, added to PNLTM before the 10 dB-down window is found and included in the reported EPNL.

Parameters

Name	Description
pnlt	The tone-corrected perceived noise levels PNLT(k), in PNdB.
dt	Per-record duration, in s (scalar broadcast or per record).
reference_time	Normalising time T0, in s (default 10).
tone_corrections	Optional tone corrections C(k), in dB, one per pnlt record; enables the bandsharing adjustment ΔB described above. Default None (no adjustment).

Returns: (epnl, pnltm, kF, kL) — EPNL in EPNdB, the peak PNLTM, and the 0-based 10 dB-down record indices (inclusive).

Raises

Exception	When
ValueError	If the inputs are invalid.

EPNLResult

EPNLResult(
    frequencies: NDArray[np.float64],
    times: NDArray[np.float64],
    pnl: NDArray[np.float64],
    tone_correction: NDArray[np.float64],
    pnlt: NDArray[np.float64],
    pnltm: float,
    bandsharing_adjustment: float,
    duration_correction: float,
    epnl: float,
    band_limits: tuple[int, int],
)

Effective Perceived Noise Level of an aircraft flyover (ICAO Annex 16).

Attributes

Name	Description
frequencies	The 24 one-third-octave band centre frequencies, in Hz.
times	Record times, in s.
pnl	Perceived noise level per record, in PNdB.
tone_correction	Tone-correction factor per record, in dB.
pnlt	Tone-corrected perceived noise level per record, in PNdB.
pnltm	Maximum tone-corrected perceived noise level, in PNdB, including the bandsharing adjustment ΔB (App. 2 §4.4.3).
bandsharing_adjustment	The bandsharing adjustment ΔB, in dB (zero unless the tone correction at PNLTM is suppressed).
duration_correction	Duration correction D = EPNL − PNLTM, in dB.
epnl	Effective perceived noise level, in EPNdB.
band_limits	The 0-based 10 dB-down record indices (kF, kL).

EPNLResult.plot()

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

Plot the PNL and PNLT time histories with PNLTM and the 10 dB-down band.

EPNLResult.report()

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

Render an ICAO Annex 16 EPNL certification fiche to a PDF.

Writes a one-page aircraft-noise-certification data sheet: the standard-basis line (ICAO Annex 16 Vol. I Appendix 2), an optional TCDSN-style metadata header (aircraft, manufacturer / type-certificate holder, applicant, measurement point), a metrics table of the informational intermediate quantities (PNLTM, the duration correction D, the 10 dB-down record window and, when non-zero, the bandsharing adjustment), the result’s own landscape PNLT-versus-time plot, the boxed EPNL = X EPNdB result, a Level | Limit | Margin verdict row when a certification limit is supplied, a static reference-conditions strip and a footer with the fixed disclaimer.

Parameters

Name	Description
path	Destination path of the PDF file.
metadata	Optional ReportMetadata; None produces a prediction fiche (metrics, plot and result only, no verdict). A supplied requirement is read as the certification EPNL limit in EPNdB (the EPNL passes at or below it).
engine	Rendering back end; only "reportlab" is supported.
verbose	Accepted for a uniform signature; it has no effect on the single-layout EPNL fiche.
language	Fiche language: "en" (default, English) or "es" (Spanish, with a comma decimal separator).

Returns: The written path as a str.

Raises

Exception	When
ValueError	If engine is not "reportlab".
ImportError	If reportlab is not installed (pip install phonometry[report]).

NOY_BANDS

Constant (numpy.ndarray, shape (24,)).

perceived_noise_level

perceived_noise_level(spl: NDArray[np.float64] | list[float]) -> float

Perceived noise level PNL (ICAO Annex 16 App. 2 §4.2), in PNdB.

N = 0.85·n_max + 0.15·Σn and PNL = 40 + (10/lg2)·lg N. If the total noisiness is not positive the PNL is defined as 0.

Parameters

Name	Description
spl	The 24 one-third-octave-band sound pressure levels, in dB.

Returns: The perceived noise level, in PNdB.

Raises

Exception	When
ValueError	If the spectrum is not 24 finite levels.

perceived_noisiness

perceived_noisiness(
    spl: NDArray[np.float64] | list[float],
) -> NDArray[np.float64]

Per-band perceived noisiness n in noys (ICAO Annex 16 App. 2 §4.7).

The analytic piecewise noy law, using the Table A2-3 constants:

• SPL ≥ SPL(a): n = 10^{M(c)·(SPL − SPL(c))}
• SPL(b) ≤ SPL < SPL(a): n = 10^{M(b)·(SPL − SPL(b))}
• SPL(e) ≤ SPL < SPL(b): n = 0.3·10^{M(e)·(SPL − SPL(e))}
• SPL(d) ≤ SPL < SPL(e): n = 0.1·10^{M(d)·(SPL − SPL(d))}
• SPL < SPL(d): n = 0 (below the noy floor)

Parameters

Name	Description
spl	The 24 one-third-octave-band sound pressure levels, in dB.

Returns: The per-band perceived noisiness, in noys.

Raises

Exception	When
ValueError	If the spectrum is not 24 finite levels.

tone_correction

tone_correction(
    spl: NDArray[np.float64] | list[float],
    *,
    start_band: int = 2,
) -> float

Tone-correction factor C for a spectrum (ICAO Annex 16 App. 2 §4.3).

The maximum over bands of the tone-correction factor derived from the tone excess F above the smoothed background, with the 1.5 dB threshold, the 500 Hz / 5000 Hz frequency split and the 6⅔ dB cap of Table A2-2.

Parameters

Name	Description
spl	The 24 one-third-octave-band sound pressure levels, in dB.
start_band	First band index of the slope analysis (App. 2 §4.3.1 Step 1). The default 2 (80 Hz) is the aeroplane procedure; helicopters and tilt-rotors use 0 (50 Hz).

Returns: The tone-correction factor C, in dB (0 if no tones qualify).

Raises

Exception	When
ValueError	If the spectrum is not 24 finite levels.