Dolby Noise Reduction

A series of noise reduction systems developed by Dolby Laboratories for use in analogue magnetic tape recording and playback. All of the Dolby variants work by companding; i.e. compressing the dynamic range of the sound during recording, and expanding it during playback.

The best known of the systems is probably Dolby B, which was introduced to the home market in 1968, but still remains common on stereo tape players and recorders today. Other consumer market systems include Dolby C and Dolby S. Dolby A and Dolby SR were developed for professional use.