What is the Difference Between Diegetic Sound and Non-Diegetic Sound?
Every sound in a film falls into one of two categories: diegetic or non-diegetic. The distinction is simple but fundamental to sound design in film. Diegetic sound originates from within the world of the story. Characters can hear it. Non-diegetic sound comes from outside the story world. Characters cannot hear it, but the audience can.
Understanding this difference shapes every decision a filmmaker makes about audio, from what a production sound mixer captures on set to what a sound designer layers in during post-production. It’s also one of the most tested concepts in film school and one of the most frequently referenced in academic film analysis.
WHAT IS DIEGETIC SOUND?
Diegetic sound is sound that originates within the film and a real sound which actually takes place during the scene and appears to have a place in the scene either on the screen or off. The concept was originally developed by film theorists Claudia Gorbman and Michel Chion. For the academic framework, Yale Film Studies’ overview of film sound covers how diegetic and non-diegetic sound function in narrative cinema.
For instance, in a scene with an individual driving a car, a horn honking would be considered a diegetic sound. Any sound that is real, or anything that has the potential to make sound within the frame is a diegetic sound.
Even a sound that comes from somewhere off the screen, but is a legitimate real sound that goes along with the purpose of the scene, is considered a diegetic sound.
FOR EXAMPLE
Diegetic sounds, or the items producing the diegetic sound, may not be seen on the screen. For example, if you see a police officer driving his car to an emergency, and hear a siren, the sound is diegetic.
You don’t have to see the siren or the lights. But the sound is a legitimate sound with a natural source. And therefore, it is a diegetic noise or diegetic sound.
DIEGETIC SOUND EXAMPLES
- The conversation of two or more characters on the screen.
- The conversation between characters off the screen in the background.
- Music being played in a restaurant.
- A piano being played in a home.
- Background music that is heard inside a bar.
- A street performer playing a guitar on the corner of a city block.
- Sound effects that simulate rain drops on a tin roof.
- Sound effects that simulate the squealing of wind outside a house.
As these examples show, diegetic sounds are all natural, real sounds that would logically exist in the scene. Even when they’re recreated using foley and sound effects techniques, the simulated rain or wind is still considered diegetic because those sounds have a believable source within the story world.
Classic film examples of powerful diegetic sound include the typewriter in All the President’s Men, the breathing inside Darth Vader’s mask in Star Wars, and the ticking clock in Dunkirk. Each sound exists within the film’s world and serves both a practical and dramatic function.
WHAT IS NON-DIEGETIC SOUND?
Non-diegetic sound is a sound that is from a source outside the primary scene or story. Non Diegetic sound has a source that is not visible on the screen and which has not been implied as being present on the screen.
There is no source on the screen for the non-diegetic sound which is clearly added in and are not understood to be commonly present or expected for the scene in which they are shown.
Non-diegetic sounds are typically added during post-production and include voiceover narration, musical scores, and stylized sound effects. When you hear voiceover narration in a film, the characters on screen cannot hear it. When a film score swells during an emotional scene, that music exists only for the audience. When a cartoon character falls and you hear a slide whistle, that sound has no source in the story world. For a deeper academic treatment, the Filmsound.org glossary maintained by film sound professionals provides comprehensive definitions of diegetic, non-diegetic, and meta-diegetic sound categories.
COMMENTARY SOUND
Sometimes referred to as commentary sound, non-diegetic sound enters the story from outside and serves the audience rather than the characters. The most common form is the film score, composed music that sets the emotional tone for a scene. Understanding sound theory in film helps filmmakers make deliberate choices about when non-diegetic elements enhance a scene versus when they distract from it.
Non-diegetic sounds are typically added in during post-production. The most common form of non-diegetic sound is music that is added in to a scene following the shoot and which does not appear to be a natural element for the scene.
For instance, music that is playing as a scene transitions but not as a secondary accompaniment to the scene in which it is naturally occurring would be non-diegetic.
Likewise, music that is playing in a scene and appears to be coming from a car radio or some other source present to the scene would be considered diegetic.
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NON-DIEGETIC SOUND EXAMPLES
Non-diegetic sound examples can take many forms and often include character narration, soundtrack or music overlays, or sound effects that are not present in the film-world or which do not appear naturally from the real world.
FOR EXAMPLE:
Music that is clearly not part of the natural scene is non-diegetic. The orchestral score in Inception, the synth soundtrack in Drive, and the sweeping themes in The Lord of the Rings are all non-diegetic. The characters never hear this music. It exists to guide the audience’s emotional response. This music is used to deliver dramatism to the audience whereas a melancholy piano is used to invoke emotion in the audience.
Narration that takes place through a scene for the sole purpose of helping the audience and with no purpose of guiding anyone from the actual story or in no way speaking to anyone in the story is considered non-diegetic.
Various special effects sounds that are not expected in “real life,” such as the sound of bowling pins crashing as a table breaks or the sound of synthesized string instruments when an act is performed by a character on set would be non-diegetic sounds.
IN SUMMARY
The distinction between diegetic and non-diegetic sound is one of the foundational concepts in film audio. Diegetic sound anchors the audience in the story world. Non-diegetic sound shapes how the audience feels about it. The best films use both deliberately, and the best filmmakers understand exactly when to let the world speak for itself and when to add a layer that only the audience can hear.
For a broader look at how audio shapes the entire production pipeline, our guide on sound design to final mix covers audio’s full role from pre-production through delivery. And for the technical side of capturing clean production sound, understanding ADR and voiceover in post-production explains what happens when on-set audio needs to be replaced or supplemented.
Whether you’re producing a documentary, a corporate video, or a narrative film, professional sound production makes the difference between amateur and polished. Learn more about our video production services or get a free quote to discuss your next project.
DIEGETIC VS NON-DIEGETIC SOUND: VIDEO BREAKDOWN
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