Module metrics 

ISO 3382 room acoustic metrics from a Room Impulse Response.

Computes the parameters defined in

• ISO 3382-1:2009 Acoustics — Measurement of room acoustic parameters, Part 1: Performance spaces
• ISO 3382-2:2008 Part 2: Reverberation time in ordinary rooms

Implemented here:

Metric	Definition
EDT	Early decay time — slope of Schroeder decay over 0 → −10 dB,
	extrapolated to a 60 dB drop.
T20	Slope of Schroeder decay over −5 → −25 dB, extrapolated to 60 dB.
T30	Slope of Schroeder decay over −5 → −35 dB, extrapolated to 60 dB.
C50	Clarity (50 ms): 10·log10(E_[0,50ms] / E_(50ms,∞)).
C80	Clarity (80 ms): same, for music.
D50	Definition: E_[0,50ms] / E_[0,∞) (ratio in 0..1).
Ts	Centre time: ∫ t · h²(t) dt / ∫ h²(t) dt (seconds).

All time integrations start at the direct-sound arrival (see [find_direct_sound_toa] in detection.rs) so that pre-arrival silence in the recording does not skew the result.

Each fitted line carries an r² so callers can reject reverberation times where the decay is not linear in dB (e.g. coupled rooms or noise-dominated tails).

Structs

DecayCurve

Schroeder backward-integrated decay curve of a RIR, expressed in dB relative to the curve’s peak.

Iso3382Metrics

ISO 3382 single-band acoustic metrics for one RIR.

Functions

analyze_iso3382

Compute ISO 3382 single-band metrics on a broadband RIR.

estimate_noise_cutoff

Estimate the sample index at which the RIR drops into the noise floor.

schroeder_curve

Compute a direct-sound-anchored Schroeder decay curve for a RIR.