Prints that use it play normally with current systems, and provide the extra surround channel when played over systems equipped with a new Dolby SA10 adapter. What it does It has long been known that a center screen channel is necessary to ensure the precise localization of front sounds for all viewers, including those seated off to the sides. This means that sounds can now be positioned behind the audience, opening the door to exciting new effects such as true 360 pans.
Flyovers really seem to pass overhead, rather than down the sides of the theatre.
Even ambient sound reproduction is improved, being less affected by the width of the theatre. Equally important, the new center surround channel assures that even viewers seated close to the left or right of the theatre experience the total surround ambience intended by the filmmaker. While two surround channels constituted a major step forward from the single channel of earlier formats, they nevertheless limit creativity, and viewers seated far to the left and right of the screen are at a disadvantage. Experiments showed that a center rear channel provides exciting new creative opportunities and better delineates the sound field for off-axis viewers. Skywalker staff then turned to Dolby Laboratories and Lucasfilm THX to make the new surround configuration a reality.