Why do actors mime in some scenes but not in others?

Question:For acting, the only reason I can think of is that the sound quality was not very good on location somewhere and dialogue needed to be re-recorded (called dubbing). For singing, then it is probably much easier to have a recording of a song rather than to try and get the quality needed when singing live.

Best Answer - Chosen by Asker: For acting, the only reason I can think of is that the sound quality was not very good on location somewhere and dialogue needed to be re-recorded (called dubbing). For singing, then it is probably much easier to have a recording of a song rather than to try and get the quality needed when singing live.