What are the Different Surround Sound Formats?
What is Surround Sound?
Movie theaters began upgrading their sound systems years ago to make the audio experience more dramatic by surrounding the audience with sound. Dolby Laboratories developed a system to encode multiple tracks of sound onto movie films. Later home audio equipment was developed to allow this same improved audio experience for the home theater.
Surround sound simply routes sound to individual speakers, which when placed around the room, make the sound seem to come from the proper position relative to the film. As a plane flies from on screen, over your head and into the distance behind you, the sound follows the movement of the plane from the front speakers to the rear speakers.
What is the Difference Between the Formats?
Dolby Surround is the original multichannel analog film sound format used in thousands of commercially available videocassettes, laser discs, DVDs, and television programs. When a Dolby Surround soundtrack is produced, four channels of audio information are matrix-encoded onto two audio tracks. The two encoded tracks are then carried on stereo program sources such as videotapes and TV broadcasts into the home. When played back, the signal is decoded by Dolby Pro Logic® to recreate the original four channel surround sound experience. The four channels provide left, center, right, and mono surround (which can be run through two surround speakers). Without a Pro Logic decoder, the encoded program plays in stereo.
Dolby Pro Logic® is a matrix decoder built into home theater receivers that decodes the four channels of Dolby Surround sound that have been encoded onto the stereo soundtracks of material such as VHS movies and TV shows. It delivers four channels of sound: left, center, right and mono surround to two rear surround speakers.
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