Definition: 5.1 channel sound, also known as Surround Sound, is a standard sound format found on most DVDs and some CDs. The five channels are left and right main speakers (stereo), a center channel for movie dialog and on-screen action, two rear speakers to surround the listener and a .1 channel (pronounced 'point-one channel') for bass. The .1 channel is intended for a subwoofer, used for special effects in movies and very deep bass in music. The designation '.1' means that it is not a full range channel and is designed to reproduce only a narrow range of bass tones. See LFE for more information.