"I created my own archive of how he said every word and every diphthong," says Butler.

How do you sound like Elvis Presley without becoming a parody of the King?

That was the monumental task set before Austin Butler, who stars as the rock 'n' roll icon in director Baz Luhrmann's Elvis (out June 24). In both his low-voiced drawl and Presley's instantly recognizable singing voice, Butler delivers.

For Butler, 30, it wasn't a mere process of imitation, but a painstaking period of preparation that involved breaking words down to their smallest parts.

"I'd hear him say a certain word and I would clip just that bit out so I knew how he said that word," the California-born actor explains of the minutiae of his process. "I created my own archive of how he said every word and every diphthong, and the way that he used musicality in his voice."

Butler turned to interviews and performances to help him obsessively practice. "There are so many people out there who are super-fans, who compile these websites that have the most amazing resources," he tells EW. "I scoured all of them. I looked at every YouTube video I could find and every film that I could watch, and I started making my own [sound catalog]."

He also worked with dialect coaches, rehearsing the sound of Presley's voice until he felt he could match him beat for beat, not just in sound, but in rhythm and cadence. "I would take an interview or a speech that he had on stage where he is talking to the audience, and I would practice it as though I was trying to get it to be exact," he says. "That way, I couldn't hear a difference between my voice and his. Then I would have my dialect coach there going, 'This is off a little bit,' and I'd practice. I'd just keep honing it in until I could get as specific as possible."

Butler says he also recorded himself, playing the tape over and over and listening to Presley's voice as he took walks — or even as he fell asleep.

Austin Butler plays piano as Elvis Presley
Credit: Hugh Stewart/Warner Bros.

"I broke it into time periods because his voice changed quite a lot over the course of his life," Butler says. (His performance of Presley ranges several decades, from the singer's youthful beginnings up to his death in 1977.) "So then I could break it up and go, 'Okay, what am I filming today? I'm in '62 — how does he sound here?'"

There's also the matter of Presley changing his own style of speaking, a common phenomenon among people in the public eye. "I think his voice changed a lot after he started hearing himself," Butler muses. "Some of the very early recordings, he sounds a lot more Southern, a lot more uncensored in his Southern twang. And then, he starts deepening his voice a little bit and getting a little more diligent about how he speaks."

Butler sings all of Presley's early music in Elvis (for the later Las Vegas years, his voice is blended with actual Elvis performances). The actor has been playing guitar and studying music since he was 13. "Music has always been a part of my life but always a very private thing," he says. "It was just my own form of therapy. I knew that the singing aspect of [the role] was going to be something I really wanted to give everything I had to."

To that end, Butler and the production team recruited singing coaches from New York, Los Angeles, and Australia. "I sang every day [while preparing and filming] and would do my singing exercises first thing in the morning," he says. "It is really like a muscle. Through filming, I started noticing notes that I couldn't hit in the beginning, suddenly, now I could hit those notes. I was widening my range. But it's not just singing — you're having to find vocal mannerisms. That could be a little tricky."

Director Lurhmann describes a sequence in which Butler's musical training shone through. "The scene where Elvis has to inspire his new big band in Vegas to do this modern version of 'That's Alright (Mama)' — this big concept in his mind," Luhrmann tells EW. "We rehearsed for three months to a playback tape that we had. But when I was shooting, Austin looked at me and was like, 'This just is corny. This is not working. It's fake.'"

While Butler took a short break to re-focus, Luhrmann instructed the musicians to intentionally play the notes wrong so that Butler — as Elvis — would have to work with them to get the sound he wanted.

"That's the thing with Elvis," Luhrmann says of the icon's musicality. "Elvis singing the lines, being the conductor, being the music. Elvis became the music. That's how he created. He was the music."

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