Dolby Stereo SR in 50 s

Dolby Stereo SR, which stands for “Spectral Recording”, is a multi-channel audio standard used mainly on 35mm motion picture films.
Dolby Stereo SR is the evolution of Dolby Stereo where the dynamic range (ie the difference between the peak level of the sound in relation to the background noise) has been improved.

Dolby Stereo SR has been used since 1987 as a replacement for Dolby Stereo.
The first film to use this technology was Robocop, which was released in US theaters on July 17, 1987.