Surround sound

Surround sound is a technique for enriching the sound reproduction quality of an audio source with additional audio channels from speakers that surround the listener (surround channels). Its first application was in movie theaters. Prior to surround sound, standard theater sound systems had three "screen channels" of sound, emitted by loudspeakers located only in front of the audience: at the left, center, and right. Surround sound adds one or more channels from loudspeakers behind the listener, thus is able to create the sensation of sound coming from any horizontal direction 360° around the listener. There are various surround sound–based formats and techniques, varying in reproduction and recording methods along with the number and positioning of additional channels. The most common surround sound specification, the ITU's 5.1 standard, calls for 6 speakers: Center (C) in front of the listener, Left (L) and Right (R) at angles of 60° on either side of the center, and Left Surround (LS) and Right Surround (RS) at angles of 100–120°, plus a subwoofer whose position is not critical.

Surround sound is characterized by a listener location or sweet spot where the audio effects work best, and presents a fixed or forward perspective of the sound field to the listener at this location. The technique enhances the perception of sound spatialization by exploiting sound localization; a listener's ability to identify the location or origin of a detected sound in direction and distance. This is achieved by using multiple discrete audio channels routed to an array of loudspeakers.[1]

Though cinema and soundtracks represent the major uses of surround techniques, its scope of application is broader than that as surround sound permits creation of an audio-environment for all sorts of purposes. Multichannel audio techniques may be used to reproduce contents as varied as music, speech, natural or synthetic sounds for cinema, television, broadcasting, or computers. In terms of music content for example, a live performance may use multichannel techniques in the context of an open-air concert, of a musical theatre or for broadcasting;[2] for a film specific techniques are adapted to movie theater, or to home (e.g. home cinema systems).[3][4] The narrative space is also a content that can be enhanced through multichannel techniques. This applies mainly to cinema narratives, for example the speech of the characters of a film,[5][6][7] but may also be applied to plays for theatre, to a conference, or to integrate voice-based comments in an archeological site or monument. For example, an exhibition may be enhanced with topical ambient sound of water, birds, train or machine noise. Topical natural sounds may also be used in educational applications.[8] Other fields of application include video game consoles, personal computers and other platforms.[9][10][11][12] In such applications, the content would typically be synthetic noise produced by the computer device in interaction with its user. Significant work has also been done using surround sound for enhanced situation awareness in military and public safety application.[13]

Commercial surround sound media include videocassettes, DVDs, and SDTV broadcasts encoded as compressed Dolby Digital and DTS, and lossless audio such as DTS HD Master Audio and Dolby TrueHD on HDTV Blu-ray Disc and HD DVD, which are identical to the studio master. 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 and DTS. Sony Dynamic Digital Sound (SDDS) is an 8 channel cinema configuration which features 5 independent audio channels across the front with two independent surround channels, and a Low-frequency effects channel. Traditional 7.1 surround speaker configuration introduces two additional rear speakers to the conventional 5.1 arrangement, for a total of four surround channels and three front channels, to create a more 360° sound field.

Most surround sound recordings are created by film production companies or video game producers; however some consumer camcorders have such capability either built-in or available separately. Surround sound technologies can also be used in music to enable new methods of artistic expression. After the failure of quadraphonic audio in the 1970s, multichannel music has slowly been reintroduced since 1999 with the help of SACD and 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 (see fake stereo).

In 1967, the rock group Pink Floyd performed the first-ever surround sound concert at "Games for May", a lavish affair at London’s Queen Elizabeth Hall where the band debuted its custom-made quadraphonic speaker system.[14] The control device they had made, the Azimuth Co-ordinator, is now displayed at London's Victoria and Albert Museum, as part of their Theatre Collections gallery.[15]

The first documented use of surround sound was in 1940, for the Disney studio's animated film Fantasia. Walt Disney was inspired by Nikolai Rimsky-Korsakov's operatic piece Flight of the Bumblebee to have a bumblebee featured in his musical Fantasia and also sound as if it was flying in all parts of the theatre. The initial multichannel audio application was called 'Fantasound', comprising three audio channels and speakers. The sound was diffused throughout the cinema, controlled by an engineer using some 54 loudspeakers. The surround sound was achieved using the sum and the difference of the phase of the sound. However, this experimental use of surround sound was excluded from the film in later showings. In 1952, "surround sound" successfully reappeared with the film "This is Cinerama", using discrete seven-channel sound, and the race to develop other surround sound methods took off.[16][17]

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 Brussels World's Fair, also utilised spatial audio with 425 loudspeakers used to move sound throughout the pavilion.

This page was last edited on 27 June 2018, at 16:28 (UTC).
Reference: https://en.wikipedia.org/wiki/Surround_sound under CC BY-SA license.

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