Sound recorded live on set from the actual source — dialogue, effects, ambience. Synced to picture, not ADR.
You're on set, the camera is rolling, the actor speaks their line — and precisely what comes out of their mouth while the camera is running is your original sound. Not re-recorded in a studio, not artificially added, but captured live at the moment the action takes place. This is the foundation of your sound design, and it determines how believable your scene ultimately appears.
Original sound encompasses everything the sound recordist captures during the take with a wireless microphone, a lavalier microphone, or the camera microphone — the dialogue, the rustle of a jacket, the slam of a door, the room's reverberation, the street noise behind it. Every sound that originated in that specific location under those specific conditions becomes the reference for your later mix. Even if you add ambient tracks later or insert individual effects — the original sound is the anchor that gives your scene its acoustic authenticity.
On set, you meticulously note which take delivers which original sound. Some dialogue is crystal clear, while other dialogue is intentionally mixed with background noise for the sake of atmosphere — for instance, because the scene takes place in a pub and the sound recordist captured precisely that environmental saturation. This is not a mistake, but information. In editing and mixing, you then have a choice: Do you stick with the original sound, or do you overlay Automated Dialogue Replacement (ADR) to create clarity? Do you continue using the ambient sound from the original recording, or do you construct a clean base and rebuild the sound effects from scratch?
Professional editing suites archive original sound structured by scene and take, often with TC (Timecode), so that every sound can be traced with pinpoint accuracy. The quality of the original sound — whether it's clean, whether it's mixed with wind noise, whether it's too quiet — often determines the later workload in post-production right on set. A good sound recordist on set saves you hours in the mixing studio. Neglected original sound forces you into ADR and artificial sound design later, when you would have preferred to use the actual recording.