The general reason for needing to perform ADR is because of heavy background noise that was captured while a scene was recorded. Alternative reasons include a need for better stereophonic separation or just better enunciation on the part of the actor. Occasionally, however, entirely new lines (such as narration or a correction to a scripted line) might be required to be recorded. An ADR recording session was featured on CON: Look Who's Talking. In this episode, David Tennant gave an opinion about ADR shared by many actors: