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.