THE MOST INVISIBLE CRAFT
Sound design is the craft responsible for everything you hear in a film that isn't the musical score or the recorded dialogue from the set. It is the most invisible craft in filmmaking when it works, and the most noticeable when it doesn't. When a film's sound design is excellent, you feel effects — tension, dread, wonder, the specific texture of a space — without being able to identify the mechanism producing those effects. The mechanism is the sound.
Most film viewers think about what they see when they think about a film. The sound design is operating on them constantly, shaping what they feel about what they see, and they rarely notice it doing so. Becoming conscious of it changes how you watch films.
WHAT SOUND DESIGNERS ACTUALLY DO
A film's sound environment is built from several layers. The production sound is recorded on set — dialogue, ambient environment, whatever the set microphones pick up. The foley is sounds added in post-production to replace or supplement production sound that was inadequate: footsteps, clothes movement, the sound of objects being handled. Foley artists create these sounds in dedicated studios, watching the film and performing the sounds in sync with the image.
Sound effects are designed sounds for events that have no real-world reference or whose real-world sound is insufficient for the film's purposes. The specific sound of a lightsaber was designed by Ben Burtt at Lucasfilm; it doesn't exist in nature. The specific sound of a particular weapon in a particular film is designed to carry the emotional weight the film needs that weapon to carry — not to accurately reproduce what that weapon actually sounds like, which is often less interesting than what it should sound like.
The ambient sound — the acoustic environment of the space — is one of the most powerful and least remarked elements of sound design. A room in a film sounds the way it sounds because of decisions made in post-production about reverberation, background noise, the specific acoustic character of the space. Those decisions shape how the room feels emotionally before anyone speaks in it.
HOW SOUND SHAPES WHAT YOU FEEL
The most dramatic demonstrations of what sound does to the viewer's emotional state are found in horror film — the genre where sound design is most consciously manipulated for effect. Remove the sound from a horror sequence and the images frequently become banal. The sound is creating the dread; the images are the occasion for it.
But the same principle operates in every genre. The specific sound of rain on the roof in a drama carries a specific emotional register. The way ambient sound drops out in the moment before a dramatic revelation — the acoustic equivalent of a held breath — creates tension that the image alone wouldn't generate. The absence of expected sound (silence in a space that should have ambient noise) is as designed as the presence of sound, and often more disturbing.
THE FILMS TO STUDY
Apocalypse Now (Coppola / Walter Murch, 1979): Walter Murch, who edited the film and designed its sound, created a sonic environment for the Vietnam War that remains the standard against which all subsequent war film sound design is measured. The helicopter rotors that open the film, blending with the ceiling fan, are the most anthologised sound design sequence in cinema history. Murch's book In the Blink of an Eye is the most accessible practitioner account of how sound and editing interact.
No Country for Old Men (Coen Brothers, 2007): A film with almost no musical score that uses ambient sound and silence as its primary emotional tools. The Coens and their sound designer Skip Lievsay created an atmosphere of dread from the sounds of the West Texas landscape — the wind, the footsteps on gravel, the specific acoustic of motel rooms — that the absent score would have converted into conventional thriller tension. The absence is the design.
Parasite (Bong, 2019): The sound design tracks the class architecture. The Park house sounds a specific way — openness, natural echo, the sounds of affluence. The Kim apartment sounds a different way. The underground space sounds a third way. You feel the class transition when you hear it, not only when you see it.
Remove the sound from a horror sequence and the images frequently become banal.