BBC Radio 4’s “Front Row.” “My falsetto is not as strong as it used to be and that I directly put down to some of the growling and yelling.”“My voice teacher in drama school would’ve been horrified by some of the things I did [in “Wolverine”],” he added.Jackman’s character is known for roaring when he’s letting out his iron claws.“We learned a technique [in school] of how to shout and how to yell without ruining your voice,” he explained. “However, during Wolverine, I did some screaming and yelling and things that I think did damage to my voice.”“I’m working on it.