At the cinema, the center-channel information contained in the Dolby® Digital Surround EX™ soundtrack is reproduced by speakers that are placed directly behind the audience. This adds a new dimension to the Dolby Digital 5.1 cinematic experience, bringing the action behind you to life. Dolby Digital Surround EX technology creates a fuller, more realistic sound for increased dramatic effect in the theatre.
On the film itself, the additional back surround information contained in the Surround EX soundtrack is matrix-encoded onto the regular left and right surround channels of conventional Dolby Digital 5.1 soundtracks. Even if a cinema is not equipped with the extra Surround EX speakers in the rear, the information intended for it will be played through the traditional left and right surround channels.