When people look back on Christian Bale's turn as the Caped Crusader in Christopher Nolan's "Dark Knight" Trilogy, alongside the darker tone and more serious take on Batman, they will remember the actor's signature Batman voice. The growl was as much a part of the character as his cape and cowl, and back when Bale was originally auditioning for the role, the voice was what set him apart.

As a part of the "The Dark Knight Trilogy: Ultimate Collector's Edition," Warner Bros. released clips from several audition tapes, including Bale's, and the topic of his voice came up in a new interview with Nolan as he looked back on the screen test.

When MTV News caught up with Bale during a press day for his new film "Out of the Furnace," he recalled his thought process going into the audition and what it was that made his add the gravel to his voice.

"I got there. They put me in Val Kilmer's suit. It didn't even fit properly, and I stood in it and I went 'I feel like an idiot.' What kind of guy walks around, dressed like a bat? And is then going to go 'Hello, how are you? Just ignore that I'm dressed as a bat.' Of course, he's meant to be doing this," Bale said. "If you look at the history of the guy and the pain that he went through. I went 'I can't do this in a normal voice. I have to become a beast in order to sell this to myself.' "

Even though that voice would go on to define what people thought of Batman's voice, the initial reviews of Bale's audition weren't as sterling as his later ones. "I went home that evening, and my wife said, 'How'd it go?' I went, 'I kind of did this.' And I showed her, and she went, 'Oh, you f---ed that one up, didn't you?' " he said. "Thank God they went for it."

The voice, among other elements of the character, are now so closely tied to Bale's portrayal of him, that it leaves a lot of question marks for when Ben Affleck takes over the rule in the upcoming "Batman Vs. Superman." Bale briefly mention that he imagines Affleck will have to do something else with his voice, but that he wishes him the best.

"[The voice] ain't for everybody. Ben's obviously going to have to do his own thing, but it was the only way that I could find how to get into that and to justify wearing the fricking Batsuit. Otherwise, he's just loopy beyond belief. He's loopy, but he's loopy with a method to his madness," Bale said. "I wish [Affleck] the best. You look at this kid, Batkid.... That gives the whole point. It doesn't matter which actor is playing him. He's a symbol. He's so much bigger than any actor. That's all. This little kid, he doesn't really care which actor's playing him. It's the symbol of the whole thing, and that's what makes the character so fantastic. I look forward to seeing what Ben will do with it."