psychoacoustics.roughness_ecma

Psychoacoustic roughness per ECMA-418-2:2025 (4th ed., Sottek Hearing Model).

Clean-room implementation of the roughness signal chain of ECMA-418-2:2025 (Clause 7). The shared auditory front-end (Clause 5: outer/middle-ear filter, 53-band gammatone-like filter bank, half-wave rectification, compressive nonlinearity to the specific basis loudness N'_basis(l, z) of Formula 25) is reused from .loudness_ecma; this module adds the roughness-specific chain:

• roughness-specific zero-padding (Clause 5.1.2.2) and segmentation (Clause 5.1.5.2) with the fixed block/hop s_b = 16384 / s_h = 4096 (Clause 7.1.1);
• the Hilbert envelope of each critical-band block and a factor-32 downsampling to 1500 Hz (Clause 7.1.2, Formula 65);
• the scaled envelope power spectrum Phi_E,l,z(k) (Clause 7.1.3, Formulae 66-67);
• the two-step noise reduction of the envelope spectra (Clause 7.1.4, Formulae 68-71);
• the four-stage spectral weighting (Clause 7.1.5, Formulae 72-96): peak picking with a quadratic-fit modulation-rate refinement and a bias correction, the high-modulation-rate weighting, the fundamental modulation-rate estimation, and the low-modulation-rate weighting;
• the interpolation to 50 Hz, the distribution-dependent nonlinear transform with the calibration constant c_R, and the asymmetric time smoothing (Clause 7.1.7, Formulae 103-110); and
• the average specific roughness R'(z) (Clause 7.1.8), the time-dependent roughness R(l50) (Clause 7.1.9, Formula 111) and the representative 90th-percentile single value R (Clause 7.1.10).

The optional entropy weighting of Clause 7.1.6 requires an external rotational speed signal and is not implemented (see notes-ecma418-2-roughness.md). The API is monaural: the quadratic-mean binaural combination of Formula (112) (Clause 7.1.11) is not implemented — analyse each channel separately.

The calibration constant c_R of Formula (104) is the standard’s tabulated value (not reverse-fit), and the chain reproduces the Clause 7 reference point exactly: a 1 kHz carrier 100 %-amplitude-modulated at 70 Hz with an overall sound pressure level of 60 dB SPL computes to 0.9999 asper against the defined 1 asper. Note the level convention: Clause 7 states the sound pressure level of the signal (its overall RMS level), not the level of the unmodulated carrier — a fully modulated signal whose carrier alone sits at 60 dB is +1.76 dB hot overall and reads ~4 % high.

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

EcmaRoughness

EcmaRoughness(
    roughness: float,
    specific_roughness: np.ndarray,
    bark: np.ndarray,
    centre_frequencies: np.ndarray,
    time: np.ndarray,
    roughness_vs_time: np.ndarray,
    specific_roughness_vs_time: np.ndarray,
    field: str,
)

Result of an ECMA-418-2:2025 (Sottek) roughness calculation.

roughness is the single representative roughness R in asper (the 90th percentile of R(l50), Clause 7.1.10). specific_roughness is the average specific roughness R’(z) in asper/Bark_HMS over the 53 auditory bands (Clause 7.1.8), with bark the critical-band-rate scale z (0.5..26.5 Bark_HMS) and centre_frequencies the band centre frequencies F(z). time and roughness_vs_time hold the time-dependent roughness R(l50) at 50 Hz (Formula 111); specific_roughness_vs_time is the time-dependent specific roughness R’(l50, z) (Formula 109) of shape (n_times, 53). field records the assumed sound field.

EcmaRoughness.plot()

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

Plot the roughness result (see ._plotting).

Draws the time-dependent roughness R(l50) and a specific-roughness heatmap. Requires matplotlib (pip install phonometry[plot]).

roughness_ecma

roughness_ecma(
    signal_in: np.ndarray,
    fs: float,
    field: Literal['free', 'diffuse'] = 'free',
) -> EcmaRoughness

Psychoacoustic roughness per ECMA-418-2:2025 (Sottek Hearing Model).

Parameters

Name	Description
signal_in	Calibrated sound pressure signal in pascals.
fs	Sampling rate in Hz. Signals not at 48 kHz are resampled (Clause 5.1.1).
field	"free" (default) or "diffuse" sound field, selecting the outer/middle-ear filter of Clause 5.1.3.

Returns: An EcmaRoughness with the single value R (Clause 7.1.10), the average specific roughness R’(z) (Clause 7.1.8) and the time-dependent roughness R(l50) (Formula 111).

A 1 kHz carrier 100 %-amplitude-modulated at 70 Hz with an overall level of 60 dB SPL yields 1 asper (Clause 7 calibration; reproduced to 0.9999 asper with the tabulated c_R of Formula (104)).