Hugh Jackman and Anne Hathaway star in the big screen adaptation of the hit stage show and they have revealed Hooper broke with tradition and banned vocal dubbing during the singing scenes.
The move meant the actors had to perfect their vocal performances without the help of a recording studio setting and sing along to a live pianist on set.
British actor Eddie Redmayne explains, "Normally if you are making an old school movie musical, as a group of actors we would go into a recording studio, we'd record an album and then two months later we'd arrive on set and they would play the playback and we would mime alongside it.
"The problem with that is that you have to make all your acting choices three months before you have even met the actor you're working with. By recording it live, Tom is allowing us the spontaneity of normal film acting."
Russell Crowe insists the move gave the shoot an added realism: "Every single person is singing every take live. Singing live there's an emotional level to this that just cannot be created in the studio."
Jackman admits he was nervous at first, but eventually enjoyed being able to sing live, adding, "The idea of singing live is daunting, but what it gives you is freedom... I can take a break, I can move on, I can speed up, I can slow it down - which means I just have to worry about acting it."
Hooper adds, "This has not been done with this kind of consistency in a musical before... You can tell in your bones that there is something false or unreal about people singing to playback. I thought it was an amazing opportunity to do something really groundbreaking."
Hathaway concludes, "It's gonna (sic) be different for sure. This is the first time anyone has ever tried it like this."