The Sony Guide to Home Theater 28
Home Theater Sound
About Surround Sound
Surround sound began in the movies, with the urge to convey a more convincing,
more complete audio-visual experience. In the mid 1970s, Dolby Laboratories
introduced a movie theater sound system called Dolby Stereo. During the production of
movie sound tracks, this system encoded or "matrixed" the Left, Center, Right and
Surround channels onto just two channels of the film distribution print. Dolby Stereo
gained acceptance in movie theaters. And the movie studios were quick to take
advantage. Today, thousands of movies include Dolby Stereo sound tracks.
The benefits of Dolby Stereo were confined to the movie theater as long as
television and home video were limited to just one channel of audio. But the launch of
high fidelity stereo VCRs and stereo TV broadcasting in the early 1980s changed all that.
Suddenly, you could rent a VHS Hi-Fi movie that contained the full Dolby Stereo
encoded sound track! And you could watch movies on broadcast TV that transmitted that
Dolby Stereo sound track into your home.
It was now possible to enjoy movie theater surround sound in the comfort of your
own home. High fidelity companies transformed their AM/FM receivers into "A/V"
receivers, including first Dolby Surround and then the more refined Dolby Pro Logic
decoding circuitry.
Dolby Pro Logic decoding (left) results in four channels: Left,
Center, Right and a common Surround channel. Even when
there are two Surround speakers, they are being driven with just
one Surround signal. The Dolby Digital system (right) offers
digital sound quality, better separation among the channels, a
Low Frequency Effects (LFE) channel for the subwoofer and a
separate signals for Surround-Left and Surround-Right.
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