@audio/quality

Objective audio quality metrics — how close is the processed signal to the reference?

Reference-vs-output comparison for evaluating denoisers, stretchers, codecs, resamplers. Deterministic, no model weights.

import { snr, segSnr, lsd, spectralSim, modulationDepth } from '@audio/quality'

snr(clean, processed)                   // global SNR, dB
segSnr(clean, processed)                // frame-averaged, PESQ-style clamp
lsd(a, b, { trim: 0.1 })                // log-spectral distance, dB — ~1 transparent, >5 degraded
spectralSim(a, b)                       // cosine similarity of magnitude spectra, 1 = identical
modulationDepth(out, [220, 440], 44100) // per-partial hop-rate beating ("crumble")

| fn | measures | notes | |---|---|---| | snr(clean, out) | global SNR (dB) | time-aligned inputs | | segSnr(clean, out, opts?) | segmental SNR (dB) | per-frame, [-10, 35] clamp, silence-skipped | | lsd(a, b, opts?) | log-spectral distance (dB) | trim crops edge artifacts (default 0) | | spectralSim(a, b, opts?) | spectral cosine similarity | alignment-free | | nrr(noisy, out, from?, to?) | noise-floor drop (dB) | pass a quiet-segment range | | speechAttenuation(clean, out, from?, to?) | speech-energy loss (dB) | should be ≈0 | | goertzelEnergy(data, f, sr) | single-frequency energy | Goertzel, 20% edge trim | | chordBalance(data, freqs, sr) | min/max partial ratio | 1 = balanced | | chordRetention(data, ref, freqs, sr) | chord energy kept | 1 = no loss | | modulationDepth(data, freqs, sr, opts?) | AM depth per partial | catches tremolo LSD misses |

Consolidated from the denoise and stretch families' evaluation suites. FFT via fourier-transform. MIT.