Convolution is a mathematical operation that combines two signals to produce a third. In audio, it's primarily used for convolution reverb — applying a recorded impulse response (IR) of a real space to dry audio, making it sound as if it were recorded in that space.
How it works:
- Record a short burst of sound (or a sine sweep) in a real space
- The recording captures the space's acoustic signature — its impulse response
- The convolution algorithm applies that signature to any audio in real-time
Convolution reverb produces incredibly realistic results because it uses actual acoustic data. The downside is higher CPU usage compared to algorithmic reverbs. In game audio, convolution reverbs are sometimes used for pre-rendered cutscenes, while algorithmic reverbs handle real-time gameplay.