Diegetic Sound

Diegetic sound is audio that exists within the narrative world of a video — sound that the characters on screen could theoretically hear. A conversation between two people in a scene is diegetic. The sound of a door closing behind them is diegetic. A radio playing music in the corner of the room is diegetic. Even a character's internal monologue spoken aloud can be diegetic if the story establishes that they're speaking, not just thinking. The term comes from the Greek word "diegesis," meaning narrative or story world.

Non-diegetic sound — sometimes called "extradiegetic" — is audio that the characters cannot hear, added by the filmmakers from outside the story world. A film score underlaid beneath a scene is non-diegetic. Voiceover narration is typically non-diegetic unless the story establishes the narrator as a character within the world. Sound effects added in post-production that weren't part of the original scene recording (a whoosh under a graphic transition, a subtle drone under a tense moment) are non-diegetic.

The distinction matters for storytelling and for audio mixing decisions. When a film transitions from non-diegetic music to diegetic music — as when a scene's background music is revealed to be coming from a car radio in the next shot — it's called a "motivated sound transition" or "source cue," and it's a technique that smoothly blurs the line between atmospheric and narrative audio. For B2B video, most sound is non-diegetic (background music, voiceover) or captured diegetic (presenter's dialogue, product interaction sounds). Understanding the distinction helps producers make intentional choices about what sound is narrative versus atmospheric.