Diegetic sound

Diegetic sound belongs to a story’s world and can be heard by its characters, whether its source appears on screen or not.

Non-diegetic sound: Sound added for an audience that does not belong to the story world or reach its characters. Its contrast defines diegetic sound: characters cannot hear the score or narration in the same way.
Acousmatic sound: Sound heard without its source being shown or identified. An unseen source can still be diegetic when it exists within the story world.
Foley: The performance and recording of everyday sound effects synchronized to picture. Foley supplies footsteps, clothing rustle, and other diegetic sounds during postproduction.
Dramatic irony: A narrative effect in which an audience knows something that one or more characters do not. Audience-only sound can create an information gap between viewers and characters.
Singin' in the Rain: A 1952 musical comedy film directed by Gene Kelly and Stanley Donen. Its musical numbers turn songs into performances heard within the story world.
Film sound: The organized use of speech, music, effects, and silence in motion pictures. Diegetic sound is one part of film sound, classified by its place in the story world.
Synchronous sound: Sound aligned in time with the visible action that appears to produce it. Synchronization makes a visible story-world action seem to produce its diegetic sound.
Sound design: The creative shaping of sound for film, games, and other media. Sound design builds the acoustic world in which diegetic sounds have meaning.
Suspense: An emotional response to uncertainty about an anticipated outcome. An unexplained diegetic noise can make characters and audiences anticipate danger.
The Godfather: A 1972 crime film directed by Francis Ford Coppola, adapted from Mario Puzo’s novel. Its opening wedding sequence grounds music and celebration in the characters’ shared space.

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