Upward expansion make the louder sounds above the threshold even louder.Ī feed-forward compressor design (left) and feedback design (right) A noise gate can be thought of as an extreme form of downward expansion as the noise gate make the quiet sounds (for instance: noise) quieter or even silent, depending on the floor setting. Like compression, expansion comes in two types, downward and upward.ĭownward expansion make the quiet sounds below the threshold even quieter. Expansion increases the dynamic range of the audio signal. Some compressors also have the ability to do the opposite of compression, namely expansion. The louder sounds above the threshold remain unaffected. Upward compression increases the volume of quiet sounds below a certain threshold. A limiter can be thought of as an extreme form of downward compression as it compresses the sounds over the threshold especially hard. This is the most common type of compressor. The quiet sounds below the threshold remain unaffected. ĭownward compression reduces the volume of loud sounds above a certain threshold. Both downward and upward compression reduce the dynamic range of an audio signal. There are two types of compression, downward and upward. A limiter is a compressor with a high ratio and, generally, a short attack time. Compression and limiting are identical in process but different in degree and perceived effect. In recorded and live music, compression parameters may be adjusted to change the way they affect sounds. In the 2000s, compressors became available as software plugins that run in digital audio workstation software. Compression is commonly used in sound recording and reproduction, broadcasting, live sound reinforcement and in some instrument amplifiers.Ī dedicated electronic hardware unit or audio software that applies compression is called a compressor. From top to bottom: Retro Instruments/Gates STA level Spectra Sonic 610 Dbx 162 Dbx 165 Empirical Labs Distressor Smart Research C2 Chandler Limited TG1 Daking FET (91579) and Altec 436c.ĭynamic range compression ( DRC) or simply compression is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or compressing an audio signal's dynamic range.

A rack of audio compressors in a recording studio.

Multi band vs single band compressor