Dolby Analog SR or Dolby SR format (Spectral Recording), was developed by Dolby Laboratories and has been in common use since 1986. It is a revised version of the Dolby's first multichannel film sound format, Dolby Stereo (or Dolby Analog). Dolby Laboratories, Incorporated (Dolby Labs) is a company specializing in audio compression and reproduction. ... 1986 (MCMLXXXVI) is a common year starting on Wednesday of the Gregorian calendar. ... Dolby Stereo (or Dolby Analog) was the original analog optical technology developed by Dolby Laboratories for 35 mm prints in 1976. ...

Dolby analog soundtracks now incorporate Dolby SR technology, improving the dynamic range of analog recordings and transmissions by as much as 25 dB. Dolby SR is utilized by recording and postproduction engineers, broadcasters, and other audio professionals.

It is the benchmark in analog film sound, and is included today on nearly all 35 mm film prints. Films that include digital soundtracks also typically include a Dolby Analog SR soundtrack, which is used in cinemas not equipped for digital playback, or as a backup in case of problems with the digital track.

Sound is encoded into four channels; Left, Center, and Right all play back on speakers located behind the screen. The fourth channel, Surround, is heard over speakers at the sides and rear of the theatre, which are used for ambient sound and special effects.

Dolby Surround is the marketing name for the consumer implementation of this audio format, the term is not applicable to cinema. Sign for Dolby Surround Dolby Surround was the earliest consumer version of Dolbys multichannel analog film sound format Dolby Analog SR (Spectral Recording). ...