There’s a lot that goes into making a movie that’s easy to take for granted. Every shot requires a ton of work behind the scenes in post-production to get the color and sound and everything else just right, which sometimes requires actors to come back for key scenes. No, I’m not talking about dreaded reshoots, I’m talking about ADR — automated dialogue replacement. And the ADR for Logan was… well, it was something else.

Hugh Jackman, bless him, released this clip on his Twitter of him standing in a sound studio to record all the huffs, grunts, and yells that make up a Wolverine fight scene. As the visuals play out in silence on screen in front of him, Jackman has to substitute his own sounds for all the action that’s going on. You don’t see very much of the actual scene, so don’t worry about spoilers.

ADR happens all the time, probably way more than you realize. And especially for a scene like this, where the actors are running through woods with nowhere to put any microphones, and the camera isn’t picking up any dialogue or other noises the actors are making, it’s essential to have a contingency plan like ADR or the sound in the scene just won’t sound right. In less extreme cases, actors are usually brought back in to re-record dialogue that wasn’t picked up correctly during the initial shoot, and even record dialogue that happens offscreen.

Next time you watch an action scene, remember that all those grunts and huffs were recorded by the actors after the fact, running in place in a small room, watching themselves on a TV screen.

Logan in currently in theaters.

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