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How Surround Sound Works

Early Surround

Over the years, there have been many different approaches to surround sound. Walt Disney's "Fantasia" (1941), one of the earliest surround-sound movies, immersed the audiences in classical music. Disney sound engineer William Garity took separate recordings of each orchestra section and mixed them to produce four distinct audio tracks, which were recorded as optical tracks on a separate reel of film.

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The four tracks drove different speakers positioned around the theater. In an equipped theater, the music seemed to move around the auditorium, an effect achieved by sound panning. Panning involves fading a sound (a violin melody, for example) from one audio channel while building it on another.

To show "Fantasia" in surround sound, a theater needed an additional projector to play just the soundtrack, as well as an expensive receiver and speaker assembly. (Check out Film Sound History for a thorough history of how "Fantasound" came about.)

This surround-sound system didn't catch on (the necessary equipment was prohibitively expensive), but by the late 1950s, many Hollywood movies were encoded with simpler multi-channel formats. Several different theater setups emerged in this era, including the famous Cinerama and Cinemascope, but most of them used the same basic sound technology. As a whole, these systems were referred to as stereophonic sound, or simply theater stereo.

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