Impulse Response (IR)
Definition
A recording that captures the acoustic signature of a physical space or hardware device by measuring its response to a brief, full-spectrum test signal. Impulse responses are used in convolution reverb processors to recreate real acoustic environments digitally.
In Simple Terms
A recording that captures the acoustic fingerprint of a real space or piece of equipment. Load it into a convolution reverb and your audio sounds like it was recorded in that specific room, hall, or studio.
In Practice
An impulse response of a vintage EMT 140 plate reverb unit is loaded into a convolution reverb plugin, allowing the engineer to apply the exact tonal and spatial character of that hardware to any signal without owning the original unit.
Common Confusion
A high-quality IR is not a guarantee of high-quality reverb. The IR captures the linear response of a space or device — not the non-linear behavior (saturation, modulation, dynamic compression) that often defines analog gear. A convolved EMT 140 IR sounds like the plate; it does not sound exactly like driving a real plate hard.
Sources & Verification
- Farina, A. — Simultaneous Measurement of Impulse Response and Distortion with a Swept-Sine TechniqueAES 108th Convention, 2000
- Välimäki, V. et al. — Fifty Years of Artificial ReverberationIEEE Trans. on Audio, Speech, and Language Processing, 2012
Last verified: 2026-05-05