The document discusses the use of sound in film. There are two types of sound: diegetic, which comes from visible or implied sources within the story, and non-diegetic, which is added during editing. Sound can help set the mood and genre, manipulate audience emotions, and provide cues about characters' feelings and upcoming events. Horror film soundtracks commonly use suspenseful notes, changes in pitch, echoed voices, and alien and screaming effects to startle and unnerve the audience. When creating an opening sequence, appropriate music will be selected and edited to shots to successfully set the mood.