aircraft.certification

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 — $\mathrm{PNL}=40+(10/{\log }_{10}2)\cdot {\log }_{10}N$ from the total noisiness $N=0.85\cdot n_{\max }+0.15\cdot \sum n$.
• 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 $\mathrm{PNLT}=\mathrm{PNL}+C$, the maximum PNLTM, the 10 dB-down integration limits and the duration correction, giving $\mathrm{EPNL}=\mathrm{PNLTM}+D$.

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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 $\mathrm{PNLT}=\mathrm{PNL}+C$; the maximum PNLTM and the duration correction over the 10 dB-down window give $\mathrm{EPNL}=\mathrm{PNLTM}+D$.

Parameters

Returns: An EPNLResult.

Raises

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).

with the 10 dB-down integration limits about the maximum PNLTM. The exact $-10\cdot {\log }_{10}(T_0)$ 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

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

Raises

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

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(
    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

Returns: The written path as a str.

Raises

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

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

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

$N=0.85\cdot n_{\max }+0.15\cdot \sum n$ and $\mathrm{PNL}=40+(10/{\log }_{10}2)\cdot {\log }_{10}N$. If the total noisiness is not positive the PNL is defined as 0.

Parameters

Returns: The perceived noise level, in PNdB.

Raises

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:

• $\mathrm{SPL}\ge \mathrm{SPL}(a)$: $n=10^{M(c)\cdot (\mathrm{SPL}-\mathrm{SPL}(c))}$
• $\mathrm{SPL}(b)\le \mathrm{SPL}<\mathrm{SPL}(a)$: $n=10^{M(b)\cdot (\mathrm{SPL}-\mathrm{SPL}(b))}$
• $\mathrm{SPL}(e)\le \mathrm{SPL}<\mathrm{SPL}(b)$: $n=0.3\cdot 10^{M(e)\cdot (\mathrm{SPL}-\mathrm{SPL}(e))}$
• $\mathrm{SPL}(d)\le \mathrm{SPL}<\mathrm{SPL}(e)$: $n=0.1\cdot 10^{M(d)\cdot (\mathrm{SPL}-\mathrm{SPL}(d))}$
• $\mathrm{SPL}<\mathrm{SPL}(d)$: $n=0$ (below the noy floor)

Parameters

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

Raises

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

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

Raises