Diegetic Sound
Sound whose source is visible on the screen or whose source is implied to be present by the action of the film.
In depth
If the characters can hear it, it's diegetic. This includes dialogue, footsteps, or music coming from a radio in the scene. 'Non-diegetic' sound is added in post-production for the audience only (like the soundtrack).
Example
“A character turns on a car radio and music plays. This is diegetic sound.”
Origin and history
The diegetic/non-diegetic distinction comes from narrative theory, particularly the work of Gérard Genette in the 1970s. The word 'diegesis' is Greek for 'narrative' or 'story-world.' Film scholars adopted the framework because cinema, more than any other medium, constantly slides between sounds that exist inside the story and sounds that exist only for the audience — and audiences accept this slide without noticing it.
Why filmmakers use it
How sound designers handle the boundary between diegetic and non-diegetic is one of the most powerful tools in film. Bringing a non-diegetic score into the diegesis (a song on the soundtrack turning out to be playing on a character's record player) reorients the audience's relationship to the scene. Modern filmmakers like the Coen brothers and Edgar Wright play with this boundary constantly, and the effect is one of the reasons their films feel so musically alive.
More examples in cinema
- The needle drop on 'Tiny Dancer' in 'Almost Famous' is diegetic — the band is singing along on the bus.
- In 'Apocalypse Now,' the helicopters arrive flying to 'Ride of the Valkyries' — diegetic, because the soldiers are blasting it from speakers mounted on the choppers.