The document defines and describes various types of sounds that can be used in films, including dialogue between characters, diegetic sounds that characters can hear within the film's world, non-diegetic incidental music and sound effects added in post-production to set mood or reinforce action, sound bridges that carry sound between scenes, and voiceovers where a character speaks their thoughts over a scene. It also mentions that the soundtrack incorporates all audio, and background music is used to add atmosphere.