An Impulse Response (IR) is an audio recording
used to recreate the acoustic characteristics of a specific environment or filter. Recording a gunshot or a balloon pop provides a good approximation of a space's impulse response. More accurate measurement techniques use swept sine waves or other specially encoded signals to minimize unwanted noise.
Whether depicting a real space (such as a church with lots of echo), or
a specific piece of audio gear (such as a classic tape machine), an impulse response
allows one to digitally apply the sound captured by the IR.
Convolution
Convolution is the process of applying the audio characteristics of an
impulse response to another audio signal. The impulse response is 'convolved'
with an incoming signal, say a vocal or guitar track, creating the effect of playing the
unprocessed audio in the same environment in which the impulse response was recorded. For a precise mathematical definition, see Convolution - from Wolfram MathWorld.
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