the use of sound is easy in this clip use a character theme though out the trailere. Character themes are normaly used for when a (normaly) villan comes to play but they are also used commenly in super hero movies to the sound creats tention as it speeds up when jaws is just about to attack. this creates a relationship to the character to the audience, meaning when the sound is played ther know who it is concted to on this case it is jaws.