VHT Articles Section - Surround Sound

* article source: http://en.wikipedia.org/wiki/Surround_sound

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Multichannel audio is the name for a variety of techniques for expanding and enriching the sound of audio playback by recording additional sound channels that can be reproduced on additional speakers. Surround sound refers to the application of multichannel audio to channels encircling the audience (generally some combination of left surround, right surround, and back surround) as opposed to "screen channels" (center, [front] left, and [front] right), i.e. around 360° in the horizontal plane (2D). The sphere (3D) of human hearing perception can be approached by adding channels above and below the listener.

One of the first documented uses of surround sound was implemented in 1940 for Disney's classic animation, Fantasia. Dubbed 'Fantasound' it consisted of three audio channels which were diffused (panned—initially live by an engineer) around the cinema over up to 54 speakers, which was achieved through the use of the sum and the difference of the phase of sound.

Surround sound technology is used in both cinema and "home theater" systems, games consoles and PCs and a growing number of other applications.

Consumer surround sound formats include sound on videocassettes, Video DVDs, and HDTV broadcasts encoded as Dolby Pro Logic, Dolby Digital, or DTS. Other formats include the competing DVD-Audio (DVD-A) and Super Audio CD (SACD) formats; and MP3 Surround.

Theatrical film 5.1 surround formats include Dolby Digital, DTS, and Sony Dynamic Digital Sound (SDDS).

Surround sound hardware is mostly used by movie productions and sophisticated video games. However, some consumer camcorders have surround sound capability either built-in or available as an add-on. Some consumer electronic devices (AV receivers, stereos, and computer soundcards) have digital signal processors or digital audio processors built into them to simulate surround sound from stereo sources.

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