After introducing the use of Dolby A-type noise reduction to the film industry, Dolby’s next major contribution was Dolby Stereo. This contribution allowed movie makers to put 4 channels (hmm… most people call that quad) of sound information on motion picture release prints using matrix technology, and gave theaters the ability to replay this 4-channel format for the movie going public. The four channels were actually left, right, center, and surround. This was the precursor to (and actually the theater version of) what became known as Dolby Surround.
