For Renée Zellweger, becoming Judy Garland took more than a pair of ruby slippers.
To prepare for her role as the Hollywood icon in Judy, Zellweger, 50, tells PEOPLE she studied hours of personal audio recordings, bootleg music performances and interviews.
“I tried to break it down from an intellectual perspective and look at the methodology behind it,” she says. “Like, okay there’s a style of singing here, and what octave she’s singing in, and what the damage at that time in her life in terms of her performances. What are those things that are defining characteristics in terms of her performance choices? And I’d try to study those.”
Judy chronicles the tumultuous final months of Garland’s life, when the famed Wizard of Oz star arrived in London to perform sold-out shows at the Talk of the Town nightclub.
Zellweger’s transformative performance has already earned her several awards at the Golden Globes, Critics’ Choice and BAFTA ceremonies. Next, she’ll compete for Best Actress at the Oscars.
At first, the role intimidated the Texas-born actress.
“I tried not to think too much about the obvious, which is how adored Judy is and has been through generations,” she says. “I tried to take that off the table and look at it as an exploration of trying to understand the human experience on the other side of that stardom … otherwise I would have just run away.”
Zellweger had to train her voice to both sing at Garland’s low register and speak in her raspy tone, weathered by years of alcohol and drug abuse.
“I never tried to hit any of those notes before — I mean, maybe in the shower it was a good idea,” Zellweger says. “So I started the vocal training and the practical training that I could, just to see what that felt like and to see what was necessary in order to actually make that sound.”
Judy marks Zellweger’s return to Hollywood after a mostly quiet decade. She feels she understands Garland somewhat from having also spent time in the spotlight.
“I have a little bit of understanding about what it’s like to live with a public persona,” Zellweger previously told PEOPLE. “I understand the vast gulf between what is written about that persona and the truth of their life.
Zellweger’s dynamic, empathetic portrayal of the star has made Judy — and Zellweger — the talk of awards season.
“When you’re portraying non-fictional accounts of people’s lives there’s a different kind of responsibility you feel to represent what could be known as accurately as possible,” she said.
The 92nd Annual Academy Awards will air live from the Dolby Theatre in Hollywood on Feb. 9 at 8 p.m. ET on ABC.