Audio Dynamic Range Compression
Mark Kolber, Daniel Lee · 2007
This chapter introduces the basic design of an audio compressor, and shows how variations such as the expander can be created with minor modifications to the basic algorithm. An audio compressor is a device that is used for automatic control of the dynamic range of audio signals with a minimal alteration to the frequency composition of the signal. Compression can be used to reduce the dynamic range of the audio material before it passes through a system so that it fits within the available dynamic range. Compression is also often used in audio and video tape recording equipment to automatically set the correct recording level despite changes to the input level. Audio compressors are characterized by their steady state input/output level characteristics which are described by threshold and slope, or ratio, or compression ratio. Compression can be used to fit the dynamic range of an audio program into the dynamic range of the equipment with the least audible effect.