This document discusses sound techniques in film. It defines diegetic and non-diegetic sound and provides examples. Non-diegetic sound, like music, can establish mood, atmosphere, and meaning without being part of the film's world. Diegetic sound belongs to the film's world and can reveal characters' states of mind. The document analyzes the non-diegetic score in Jaws, which builds tension without showing the shark. It also discusses how diegetic sounds in Rear Window establish the setting and protagonist's detached frame of mind. Sound can create meaning by enhancing emotion, setting mood, and identifying characters.