@audio/denoise-spectral

Spectral subtraction (Boll 1979) with Berouti over-subtraction + spectral floor

npm install @audio/denoise-spectral

import specsub from '@audio/denoise-spectral'

Power spectral subtraction with over-subtraction and a spectral floor (Berouti, Schwartz & Makhoul 1979): |Ŝ|² = |Y|² − α·N̂ where that stays above β·N̂, else β·N̂. Over-subtraction takes out the noise's peaks that plain subtraction leaves as musical tones; the floor, a fraction of the noise estimate, fills the valleys with a steady bed that masks what is left. α follows the frame's SNR (4 − 3/20·SNR: 4.75 at −5 dB down to 1 at 20 dB) unless fixed. The noise PSD is tracked by minimum statistics (Martin 2001) over a 1.5 s window, in batch and stream alike, unless a profile or a noise-only stretch is given; a held note, a sustained vowel or a chord is kept out of it (@audio/noise-estimate's partials, as omlsa has it: clean music cut by more than 3 dB 10.3 → 3.2 %, sung long tones 36.9 → 0.0 %, Slakh mixes 13.1 → 0.8 %; estimator: { partials: false } turns it off). processor(opts) is the gain as an @audio/stft frame process, for a host running its own frames.

specsub(data, { fs })                                          // α(SNR), β 0.05, noise tracked
specsub(data, { fs, alpha: 2 })                                // fixed over-subtraction
specsub(data, { fs, noiseFrames: 6 })                          // noise from the first 6 frames

| Param | Default | | |---|---|---| | alpha | α(SNR) | Fixed over-subtraction factor; omitted (or 0): Berouti's α(SNR) | | beta | 0.05 | Spectral floor, a fraction of the noise estimate: higher leaves less musical noise and more noise | | frameSize | power of two nearest 32 ms | STFT frame: 512 at 16 and 22.05 kHz, 1024 at 44.1, 2048 at 48 (frame(fs)) | | hopSize | frameSize/4 | OLA hop | | profile | tracked | Noise PSD (Float64Array, frameSize/2+1 bins) | | estimator | | Minimum statistics options (@audio/noise-estimate minStats); { partials: false }: held notes learned as noise, as before | | noiseFrames / profileFrom / profileTo | | A noise-only stretch to average for the profile |

Use when: quick baseline; offline cleanup with a known noise-only preamble. Not for: musical-noise-sensitive material — use wiener or omlsa.

Part of @audio/denoise — the denoise family umbrella. This README is generated from the umbrella docs.

MIT © audiojs