Many people may assume that acting is an organic process. You react to the scene, look at other people around you and try to convey the emotional reality of what’s going on in the story. But it can be surprising to learn just how little usable audio is recorded when each scene is filmed, and how much has to be recorded after the fact.
Which is why Hugh Jackman, like most actors in this sort of movie, has to spend a lot of time in the studio grunting and yelling into a microphone while pantomiming the action that’s going on in the scene. You really have to give it your all to get a performance that sounds natural, and the process can look a bit on the silly side if you’re not used to seeing this sort of post-production work.