Dolby digital is a digital audio system requiring a license that has been developed by Dolby Laboratories for movie theaters and home movie systems. Dolby digital supports mono channels, stereo channels or up to five separate main channels plus one low-frequency channel. It is used in digital TV, on DVDs and in movie theaters. Dolby digital supports up to six channels and uses a psychoacoustic, lossy method for data compression.
The sound information contained in each of the six available channels is distinct and independent. These six channels are described as a "5.1-channel" system, because there are five full-bandwidth channels with 3 Hz to 20 kHz frequency range for front left and right, center, and surround, plus one low-frequency-effects (LFE) subwoofer channel dedicated to frequencies from 3 Hz to 120 Hz.