Page "Dubbing (filmmaking)" Paragraph 4

In conventional film production, a production sound mixer records dialogue during filming.

Accompanying noise from the set, equipment, traffic, wind, and the overall ambiance of the surrounding environment often results in unusable production sound, and during the post-production process a supervising sound editor or ADR Supervisor reviews all of the dialogue in the film and decides which lines will have to be re-recorded.

ADR is also used to change the original lines recorded on set in order to clarify context, or to improve the actor's diction and timing.