An impulse response (IR) is a recording that captures how a space or system responds to a brief burst of energy. When used with convolution processing, an IR can make any dry audio sound as if it were recorded in that space.
How IRs are captured:
- Starter pistol / balloon pop — a sharp, broadband burst
- Sine sweep — a tone that sweeps through all frequencies (more precise)
- The recording is then deconvolved to extract the pure impulse response
IRs aren't limited to rooms — they can capture the character of guitar cabinets, vintage hardware, or any acoustic system. Many free IR libraries are available online for various spaces from concert halls to parking garages.