Surround sound, using multichannel audio, encompasses a range of techniques for enriching (expanding and deepening) the sound reproduction quality, of an audio source, with additional audio channels reproduced via additional, discrete speakers. The three-dimensional (3D) sphere of human hearing can be virtually achieved with audio channels above and below the listener. To that end, the multichannel surround sound application encircles the audience (left-surround, right-surround, back-surround), as opposed to "screen channels" (center, 1 left, and 2 right), i.e. ca. 360° horizontal plane, 2D).

Surround sound technology is used in both cinema and "home theater" systems, video game consoles, and personal computers, et cetera. Commercial surround sound formats include videocassettes, Video DVDs, and HDTV broadcasts encoded as Dolby Pro Logic, Dolby Digital, or DTS. Other commercial formats include the competing DVD-Audio (DVD-A) and Super Audio CD (SACD) formats, and MP3 Surround. Cinema 5.1 surround formats include Dolby Digital, DTS, and Sony Dynamic Digital Sound (SDDS).

Mostly film production companies and video game creators are the principal users of surround sound, however some consumer camcorders have such capability, either in-built or discrete. Also these technologies can be found in music, where it gives new methods for artistic expression. After quadraphonic failure in the 1970s, multichannel music has slowly been reintroduced since 1999 with the help of SACD & DVD-Audio formats. Some AV receivers, stereophonic systems, and computer soundcards contain integral digital signal processors and / or digital audio processors to simulate surround sound from a stereophonic source.

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History

The first, documented use of surround sound was in 1940, for the Disney studio's animated film Fantasia. Its multichannel audio application was called 'Fantasound', comprising three audio channels and speakers. The sound was diffused throughout the cinema, initially by an engineer using some 54 loudspeakers. The surround sound was achieved using the sum and the difference of the phase of the sound. In the 1950s, the German composer Karlheinz Stockhausen experimented with and produced ground-breaking electronic compositions such as Gesang der Jünglinge and Kontakte, the latter using fully discrete and rotating quadraphonic sounds generated with industrial electronic equipment in Herbert Eimert's studio at the Westdeutscher Rundfunk (WDR). Edgar Varese's Poeme Electronique, created for the Iannis Xenakis designed Philips Pavilion at the 1958 Paris World's Fair, also utilised spatial audio with 425 loudspeakers used to move sound throughout the pavilion. There are also many other composers that created ground-breaking surround sound works in the same time period.