The big idea: almost nothing you hear in a movie was recorded on set the way you hear it. Footsteps, punches, rain, the room's air, the music, the silence: each was chosen, built and placed by someone. Picture tells you what is happening; sound tells you how to feel about it. And because it works best when you don't notice it, most viewers never do.
What you hear in a film, layer by layer:
| Layer | Made from |
|---|---|
| Dialogue | on set or ADR |
| Effects | Foley + designed |
| Ambience | room tone, the world |
| Music | score + songs |
All four are mixed into one track.
Layer 1: Dialogue, often re-recorded
Sets are noisy: generators, traffic, wind, crew. Much dialogue is cleaned up, and some is re-recorded later in a studio, with actors watching themselves and matching their lips. This is ADR (automated dialogue replacement). Good ADR is invisible. Bad ADR is the moment a voice suddenly sounds like it's in a closet while the actor is on a windy beach.
Sound crews also record room tone: a minute or so of "silence" in each location, with everyone standing still. Real rooms are never silent, and that recorded hush gets laid under edited dialogue so the cuts don't punch holes in the air.
Layer 2: Foley, the art of fake footsteps
Most everyday sounds of people moving are added afterward by Foley artists, named after Jack Foley, who worked at Universal from the silent era and helped pioneer the craft when studios switched to synchronized sound around Show Boat (1929). They watch the film and perform sounds in sync: footsteps on a dozen floor surfaces, the rustle of clothes, a cup set down.
The props are wonderfully strange:
| Sound on screen | What made it |
|---|---|
| Footsteps in snow | Cornstarch squeezed in a leather pouch |
| A horse's hooves | Coconut shells (padded) |
| Bones cracking | Frozen lettuce, or walnuts crushed on a hard floor |
| A bird's wings | A pair of gloves flapped together |
The best Foley, as practitioners say, is so well blended that the audience never notices it.
Picture tells you what is happening. Sound tells you what it means, and how close it is to you.
Layer 3: Designed sounds, things that don't exist
What does a laser sword sound like? A dinosaur? A spaceship engine in a vacuum, where in reality there would be no sound at all? Somebody has to invent it.
For Star Wars (1977), Ben Burtt built a whole universe from real recordings: the projector-and-television lightsaber; blasters from a hammer striking the guy-wire of a radio tower; R2-D2 partly from his own voice run through a synthesizer. He received a special Academy Award for the film's alien, creature and robot voices. He also dug an old scream off a studio sound reel, first used in Distant Drums (1951), and named it the Wilhelm scream after a character in The Charge at Feather River (1953). It has since become an in-joke; one museum estimate puts it in more than 400 films. Who actually voiced it is uncertain; the singer and actor Sheb Wooley is the likeliest candidate.
For Jurassic Park (1993), Gary Rydstrom's team built the dinosaurs' voices by layering many different animal sounds. Rydstrom has won seven Oscars.
The job title itself is young. Walter Murch was the first person credited as "sound designer," on Apocalypse Now (1979), where helicopters, jungle and memory blur together. He later became the only person to win Oscars for both film editing and sound mixing, on The English Patient (1996).
Layer 4: Music, and where it comes from
Film people split sound into two kinds:
- Diegetic sound exists inside the story: a radio playing, a band at a wedding, a character humming. The characters could hear it.
- Non-diegetic sound exists only for us: the orchestral score, a narrator's voice. The characters can't hear it.
Directors play with the boundary. Baby Driver (2017) cuts its action scenes to songs the hero is playing in his own earbuds, so the soundtrack is part of the story. A score that suddenly turns out to be coming from a car radio can be a joke or a jolt.
The loudest choice: silence
Take the music away and the audience loses its guide. The Coen brothers' No Country for Old Men (2007) has only about 16 minutes of music, several of them in the end credits. In its most frightening scenes you hear wind, an engine, the beep of a tracking device, footsteps, a briefcase scraping in an air vent. With no score to tell you what to feel, every small sound becomes a threat. It won Best Picture.
How to hear it
- Close your eyes for one scene. You'll be surprised how much of the story is still there.
- Listen for the room. Does the space sound big, small, outdoors, underwater? That was a decision.
- Find a sound that "can't" exist: a spaceship in vacuum, a sword that hums, a punch that thuds like a bass drum. Ask what it's made of.
- Notice when the music stops. That's usually when the film wants your full attention.
The takeaway
Film sound is built, not captured. Dialogue is cleaned or re-recorded; footsteps and rustles come from Foley artists; impossible sounds are designed from real recordings; music is either inside the story or laid over it; and silence is a tool. Because it works best unnoticed, sound is the half of cinema most of us never consciously hear, and among the most powerful.
Try this: watch the first five minutes of any film with the picture covered or your eyes closed, then watch it again with the sound muted. Write down one thing each version told you that the other didn't.
Sources & Further Reading
Sources
- Wikipedia's sourced articles on Ben Burtt (lightsaber, Vader's breathing, blasters, R2-D2; 1977 Special Achievement Award), the Wilhelm scream (Distant Drums, 1951; The Charge at Feather River, 1953; uncertain performer), Foley (Jack Foley; props), Walter Murch (first "sound designer" credit; double Oscars for The English Patient), Gary Rydstrom (layered animal vocalizations; seven Oscars), diegesis, and No Country for Old Men (about 16 minutes of music; sound design by Skip Lievsay).
Go deeper
- 📘 In the Blink of an Eye — Walter Murch (short and profound, on film editing, by the first person credited as a film's "sound designer")
- ▶️ Making Waves: The Art of Cinematic Sound (2019, dir. Midge Costin), a documentary with Burtt, Murch and Rydstrom
- 🌐 Related pieces in this library: How Movies Manipulate You · How a Song Gets Made
For Your Vocabulary
Sound Design (the creation and shaping of a film's sounds as a creative whole) · Foley (everyday sounds performed in sync with the picture after filming) · ADR (automated dialogue replacement: re-recording lines in a studio) · Room Tone (the recorded background sound of a location with no one speaking) · Diegetic Sound (sound that exists within the story world) · Non-Diegetic Sound (sound only the audience hears, like the score) · Score (music composed for a film) · Mix (the final balance of dialogue, effects and music)