@audio/measure-ir

Impulse-response capture — exponential sine sweep deconvolution (Farina 2000), self-calibrated

npm install @audio/measure-ir

import ir from '@audio/measure-ir'

Farina exponential-sine-sweep (ESS) deconvolution: the inverse filter is the time-reversed sweep with exp(−t/L) amplitude compensation for the sweep's 1/f energy density. Convolving the recording with it collapses the sweep to an impulse at t=0; harmonic distortion products land at negative time and are trimmed away — the ESS advantage over linear sweeps or MLS. Self-deconvolution of the sweep against its own inverse filter calibrates the output so an identity system (recorded === sweep) yields δ = 1.0.

Farina, A. — Simultaneous Measurement of Impulse Response and Distortion with a Swept-Sine Technique, AES 108th Convention, 2000.

let h = ir(recorded, { sweep, f0: 20, f1: 20000, fs, length: 1000 })

| Param | Default | | |---|---|---| | sweep | — | required — the exponential sine sweep that was played (Float32Array) | | f0 | 20 | sweep start frequency, Hz | | f1 | fs/2 * 0.95 | sweep end frequency, Hz | | fs | 44100 | sample rate | | length | recorded.length - sweep.length + 1 | samples of IR to return |

Returns a Float32Array: the impulse response, direct path at index 0, calibrated to unit gain. Throws RangeError if opts.sweep is omitted.

Also exports convFFT(a, b) (zero-padded FFT convolution) and inverseSweep(sweep, {f0, f1, fs}) — the building blocks @audio/measure-align and @audio/measure-latency reuse for their own cross-correlation.

Use when: capturing the impulse response of a room, cabinet, or signal chain from a recorded exponential sweep — feeds @audio/reverb-convolution and @audio/amp-cabinet.

Part of @audio/measure — the measure family umbrella.

MIT © audiojs