Dolby Digital is the name for audio compression technologies developed by Dolby Laboratories. It was originally named Dolby Stereo Digital until 1994. Except for Dolby TrueHD, the audio compression is lossy. The first use of Dolby Digital was to provide digital sound in cinemas from 35mm film prints.
Rather than being constrained to channels, sounds can be precisely placed and moved in three-dimensional space.

A new sensation of height immerses you in the action, creating a full audio atmosphere and realistically depicting objects moving overhead.Dolby Atmos renders everything from dialogue to quiet scenes to whirlwind action with astonishing clarity, richness, detail, and depth.It all comes together in sound that excites your senses and inspires your emotions to deliver the full impact of entertainment.

Surround sound enhances the way you experience entertainment at home and in the cinema by creating the optimal environment for all of your favorite content. Whether at home or in a movie theatre, surround sound enhances the way you watch and listen to movies, music, and other entertainment. Conventional stereo creates dimensional sound in front of you. Dolby® surround sound expands on stereo to deliver sound from the sides, behind, and even above you—creating a natural, multidimensional sonic environment based on the science of how humans hear.

Dolby audio in your home theater and mobile devices improves the power, clarity, and realism of sound by offering up to 7.1 discrete surround channels and up to 9.1 channels of sound. When you go to the movies at a cinema equipped with Dolby technologies, you’ll experience state-of-the-art audio that completely envelops you in the onscreen story.

Dolby Atmos® is the latest development in realistic cinema sound. It provides full creative freedom for filmmakers and ensures that you’ll hear the soundtracks exactly as their creators intended. Dolby Surround 7.1 is a cinema audio format developed to bring more depth and realism to the cinema experience. By adding two additional discrete audio channels, Dolby Surround 7.1 takes the excitement of movies to the next level and truly immerses you in the action.