5.1 surround sound ("five-point one") is the common name for surround sound audio systems. 5.1 is the most commonly used layout in home theatres. It uses five full-bandwidth channels and one low-frequency effects channel (the "point one"). Dolby Digital, Dolby Pro Logic II, DTS, and SDDS all common 5.1 systems. 5.1 is also the standard surround sound audio component of digital broadcast and music.

All 5.1 systems use the same speaker channels and configuration, having a front left (FL) and front right (FR), a center channel (CNT), two surround channels (surround left - SL and surround right - SR) and the low-frequency effects (LFE) channel designed for a subwoofer.

History

An early predecessor to five channel surround sound appeared with the 1953 20th Century Fox film The Robe. The studio felt the film needed a larger soundstage to match its wider CinemaScope presentation and released it with four-track magnetic stereo sound with left, right, center and mono surround channels. Dolby Stereo was introduced in the 1970s, which similarly featured a four channel soundtrack.

A prototype for five-channel surround sound, then dubbed "quintaphonic sound", was used in the 1975 film Tommy, however, it had no dedicated subwoofer channel and used only two surround speakers in the rear corners of the auditorium thus causing the same problems with audience coverage uniformity that had been fixed in Fantasound (1939) by using surround arrays.