Editing Dynamic range compression (section)

=== Attack and release ===
[[File:Audio Compression Attack and Release-2.svg|thumb|220px|The attack and release phases in a compressor]]
A compressor may provide a degree of control over how quickly it acts. The ''attack'' is the period when the compressor is decreasing gain in response to the increased level at the input to reach the gain determined by the ratio. The ''release'' is the period when the compressor is increasing gain in response to reduced level at the input to reach the output gain determined by the ratio, or, to unity, once the input level has fallen below the threshold. Because the loudness pattern of the source material is modified by the time-varying operation of compressor, it may change the character of the signal in subtle to quite noticeable ways depending on the attack and release settings used.

The length of each period is determined by the rate of change and the required change in gain. For more intuitive operation, a compressor's attack and release controls are labeled as a unit of time (often milliseconds). This is the amount of time it takes for the gain to change a set amount of dB or a set percentage towards the target gain. There is no industry standard for the exact meaning of these time parameters.<ref>{{Cite journal |last1=Jeffs |first1=Rick |last2=Holden |first2=Scott |last3=Bohn |first3=Dennis |date=September 2005 |title=Dynamics Processors – Technology & Applications |url=https://www.ranecommercial.com/kb_article.php?article=2129 |journal=RaneNote |publisher=[[Rane Corporation]] |issue=155 |pages=6–7 |access-date=2012-12-21 |quote=There is no industry standard and different manufacturers define [release time] differently.}}</ref>

In many compressors, the attack and release times are adjustable by the user. Some compressors, however, have the attack and release times determined by the circuit design and cannot be adjusted. Sometimes the attack and release times are ''automatic'' or ''program dependent'', meaning that the behavior may change depending on the input signal.