The entire cast sang live while filming. Director Tom Hooper wanted to evoke real emotion from the crew and he felt that it was necessary for the crew to sing live despite any conditions they were facing during filming. Each cast member had an ear piece and off set a pianist played the melody of music for the designated scene.
Samantha Barks: “If we don’t have our ear piece in, then we look mad.”
Amanda Seyfried: “It was good that we didn’t hear the orchestra because you’re singing your emotions.”