MCU: 10 Fascinating Facts Behind The Avengers (2012)
4. How Hulk's Voice Was Created
You'd have thought that capturing the Hulk's voice would just be a matter of lower Mark Ruffalo's voice a couple of octaves, but there's a bigger blend in there than you might expect. Just as the dinosaurs in Jurassic Park were given voices made up of many different animal noises, Hulk's voice is a chorus of different people.
Sound Editor Christopher Boyes revealed that the process was a complicated one that involved taking a combination of "Mark Ruffalo, some Lou Ferrigno, and a little bit of me and two people from New Zealand."
One of the best scenes in the film comes when Hulk turns Loki into a plaything, which required some creativity. Because Hulk was rendered in CGI, having the two interact posed a challenge so the effects team tied a rope to Tom Hiddleston's leg and pulled it to show when Hulk had grabbed him. To add shock, nobody told Hiddleston precisely when that was going to happen.