Dynamic range compression (DRC) or simply compression is an electronic effect unit that reduces the volume
of loud sounds or amplifies quiet sounds by narrowing or "compressing" an audio signal's dynamic range.
Compression is commonly
used in sound recording and reproduction, broadcasting, live sound at music concerts and in some
instrument amplifiers (usually bass amps).
Audio compression reduces loud sounds which are above a certain threshold while quiet sounds remain unaffected.
In the 2000s, compressors are also available in audio software for recording. The dedicated electronic hardware
unit or audio software used to apply compression is called a compressor. In recorded and live music, compression
parameters may be adjusted by an audio engineer to change the way the effect sounds.
Compression and limiting are not different in process but in degree and perceived effect.
A limiter is a compressor with a high ratio and, generally, a fast attack time. Limiters are common as a safety
device in live sound and broadcast applications to prevent sudden volume peaks from occurring. Limiters are also
used as protective features in some components of sound reinforcement
systems (e.g., powered mixing boards and power amplifiers) and in some bass amps,
to prevent unwanted distortion and/or speaker damage.