Non-diegetic Sound

Sound in film, television, or games that does not originate from any source within the story world and cannot be heard by the characters - for example, orchestral score, voice-over narration, or added accessibility cues. This contrasts with diegetic sound, which exists in the scene (dialogue, footsteps, a radio playing on screen). The distinction matters for accessibility: audio description and earcon-style cues are inherently non-diegetic and must be designed so they are not mistaken for part of the soundtrack, while diegetic sound effects used to convey on-screen actions to blind and low-vision viewers need to sit convincingly inside the scene. Thoughtful mixing of diegetic and non-diegetic audio is a core tool of accessible film and video design.