5.1 surround sound
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, SDDS, and THX are 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 and right, a center channel, two surround channels (left and right) and the low-frequency effects channel designed for a subwoofer.