Replacing Dialogue After the Shoot

Dialogue recorded on set has to compete with everything else happening there: generators, wind, traffic, effects machinery, and other actors. When the recording is unusable, the actor records the lines again in a studio while watching the scene. The process is called ADR, or looping.

Replacing dialogue solves a technical problem and can create a creative one. A performance given on set, in costume and in the moment, is hard to reproduce months later in a recording booth. These nine commentaries describe why productions replaced dialogue, what they gained, what they risked, and how some avoided it.

§1 Noise makes the decision

Some scenes cannot be recorded cleanly at all. The Mummy Returns cut from a real jungle to a sound stage, where large fans created the wind.

The commentary adds that much of the dialogue had to be lip-synced afterward. When a scene depends on machinery that loud, replacing its dialogue is part of the plan from the start.

The Return of the King commentary describes the same problem in a scene filmed in a tin shed during a storm.

The filmmakers praise the actors for staying focused through the noise. Their performances on set were usable, but the sound was not. ADR kept the performances and replaced only the recording.

§2 What replacement can cost

The main risk of ADR is that the new reading sounds disconnected from the image. François Truffaut avoided live sound entirely on The 400 Blows. The commentary explains the risk and why it did not affect the film.

Actors re-recording their own lines can match their own timing and intention. A different voice or a long gap between filming and recording makes that harder. Truffaut’s preference came from watching dubbed American films, which suggests that a fully dubbed film can feel natural if the process is designed for it.

§3 Looping can improve a performance

ADR is not always a compromise. The Breakfast Club commentary describes editor Dede Allen changing how one of the actors thought about it.

The production recording sets a minimum: the studio version can match it or improve on it. An actor who approaches looping that way can adjust emphasis or add a reaction that was missing on the day.

The same commentary describes a technical problem with overlapping dialogue.

When an off-camera actor speaks over an on-camera one, the two voices are recorded together, and the editor cannot use either line cleanly in a different shot. Allen’s work kept many of those overlaps, which mattered in scenes where the characters interrupt each other. Directors who want overlapping dialogue need to plan for how it will be recorded and edited.

§4 Use ADR to clarify the story

New dialogue can fix a story problem the edit revealed. The Mission: Impossible III commentary describes lines added to make the action easier to follow.

The commentary also mentions adjusting dialogue to make a 30-second countdown clear. In fast action, an audience may not understand the stakes from the images alone. A line spoken off camera or over a wide shot can supply the missing information without new filming.

The Underworld: Rise of the Lycans filmmakers used ADR to change a story point.

Changing one word changed the plot: the character now understands that he has been affected. The commentary admits the scene still feels slightly odd because of the patch. ADR can repair a story point, but a change that large may still show.

§5 Replacing an actor’s voice

Sometimes a different person speaks the lines. The Two-Lane Blacktop commentary describes replacing an actress’s voice because her accent did not suit the character.

Replacing one voice affected the whole scene. A studio recording sounds different from a location recording, so the actor in the scene with her had to be re-recorded too, or the two voices would not have matched. Any replacement has to be judged against everything else in the scene’s soundtrack.

§6 Alternatives to re-recording

Some filmmakers avoid ADR when they can. The Usual Suspects commentary describes using production sound from a different take.

A line recorded on set during another take keeps the original acoustics and the actor’s performance from the same day. If the timing can be made to fit the picture, it often sounds more natural than a studio recording.

Re-recording can also be a deliberate effect. E. Elias Merhige describes processing dialogue in Shadow of the Vampire.

Voices in the film’s black-and-white scenes were re-recorded from wax cylinders to sound like early recordings. The process made the soundtrack match the period of the images.

§7 Questions before replacing dialogue

These accounts suggest five questions:

1. Can the scene be recorded cleanly at all? The Mummy Returns and Return of the King planned for replacement because of wind machines and a storm.
2. Who will re-record, and how soon? The 400 Blows worked because the actors dubbed their own lines.
3. Can looping improve the performance? The Breakfast Club commentary treats the production recording as a minimum to improve on.
4. Does the audience need a line to follow the story? Mission: Impossible III and Underworld: Rise of the Lycans added dialogue to explain action and change a plot point.
5. Is there a usable take from the set? The Usual Suspects used production sound from another take instead of ADR.

Replacing dialogue is a choice between the recording made on the day and one made later under control. The best result keeps whichever has the better performance, and plans for the scenes where the set will never allow a clean recording.