Bradley Cooper went through an incredible transformation to become Jackson Maine in “A Star is Born”, and that included entirely changing his voice.

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Appearing on Global’s “The Late Show”, the actor and director revealed to host Stephen Colbert how he managed to train his voice to go octaves lower than his real voice, making him sound more like co-star Sam Elliott.

“One of the things, I knew I wanted to lower my voice but I didn’t want to make him too ‘country’,” Cooper explained. “Sam Elliott is from Sacramento but his mother was from Texas so he has this accent that you can’t quite place but it’s so wonderfully iconic.”

Getting his voice that low, however, required a lot of warmups, which were physically demanding for Cooper. They forced him to hunch himself over for the first six months of practice.

“I would go to sleep and my throat would hurt and I thought, Well, this is never gonna happen. That was what I was most terrified of, was his voice,” he recalled. “I always had this warmup line, which was a line from an interview [Elliott] did at Sundance, which I played him when he came over to my house.”

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The warmup line in question? “This part here is about as good as it gets for me,” Cooper demonstrated.

Asked if he will try to bring back that Jackson Maine voice for his upcoming performance of “Shallow” with Lady Gaga at the Oscars, Cooper said, “He’s gone, I’m not going to try to get him back.”