Sound Definitions

Techniques : audio level compression : sound compression uses

Compression in industry

Compression is often used to make music sound louder without increasing its peak amplitude. Instead, it boosts the perceived loudness by increasing the root mean square volume. In other words, the peak of a sound wave of, say, a drum hit may be at roughly the same amplitude, but the sound is louder relative to the peak as the sound decays than it would be without compression. This reduction of the dynamics makes the drum sound louder even though it peaks at the same place. It is common to compress rock music or pop music heavily to make it sound louder without introducing undesirable distortion from higher amplitudes. This idea is also used in broadcasting to boost the perceived volume of the sound track, since broadcasters have limits on the instantaneous peak volume.

Compression as an effect

Compression can also be used on instrument sounds to give certain effects unrelated to boosting loudness. For instance, drum and cymbal sounds tend to decay quickly, but a compressor can make the sound appear to have more sustain.

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