It’s now well-known that the filmmakers and actors had a unique approach to recording the music in Les Misérables. Unlike most movie musicals in which the songs are recorded before the shoot and the cast mimes to the music, Les Misérables features the cast recorded as they were singing live. Castmembers had an earpiece in which they were accompanied by a piano, with full orchestration being done after the shoot to match the performances. However, as star Hugh Jackman tells the Associated Press, it fit right in with his past experience in musical performance.
Jackman points out that this made the shoot a rather odd experience, pointing out, “It was a weird set to go on. It was a bunch of crazy people in the rain singing. The good thing about that was, they couldn’t tell if you were hitting the wrong key because they couldn’t hear the accompaniment.” However, he later admits, “It was weird how natural it became.”
Nevertheless, Jackman explains that he this style of recording the songs ties into how he learned how to use singing in his acting. He says, “Acting through song, the way I do it is I take the lyrics off the music sheet and I write them out as dialogue, as you would break down any script — as a series of thoughts and ideas and motivations. That I needed to get under my skin first. And I learned that from Trevor Nunn (the famed theater director and director of the first English-language production of Les Misérables).”