Creating Impulse Responses

Convolution Reverb - Basics

Convolution Reverb - Basics
Figure 1: The principle of convolution reverb

The operation of convolution reverb is basically very simple: When the reverberation of sound material in convolution reverb is a reference signal in the audio stream with woven. This reference signal is invoked at each sample position and played with the current volume of the sample position. This reference signal is a room impulse response, which carries the audio information of a room.

A convolution reverb plug-in is thus nothing more than a sample player, but depending on the resolution makes it 48,000 or 96,000 times per second.

The Impulse Response

The Impulse Response
Figure 2: Spectrum and waveform from an impulse response

The impulse response is thus the cornerstone of the convolution reverb. Carries the impulse response the acoustic information of an area, it is called a room impulse response. Since we only deal in this tutorial with room impulse responses, are here meant with impulse responses room impulse responses.

The impulse response defines the sound of a room. It is called by the reverb plug-in and involved at each sample position and thus generates a reverb signal, which consists according to the nature of the impulse response. Impulse responses may consist of acoustic information that have been obtained from using spaces with bang or sweep method. We then speak of a room impulse response. Impulse responses can be every audio signal. From here, we turn to the experimental level, and via synthetic or clay material collected sound effects create entirely new effects. Finally, the reverb plug-in no matter what is used for impulse response and also as long as the sufficient computing power. The integration of the impulse response requires a lot of computing power and places high demands on a system.

Author: Guido Helbling, Avosound

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