Jennifer Hudson is not the only aspiring diva who has ever tried to scale the challenging “And I’m Telling You” and “I Am Changing” in the privacy of her living room.

The two “Dreamgirls” signature songs memorably delivered by Jennifer Holliday, who won a Tony in the role of Effie White, have captivated entire generations of young singers — even those, who like Hudson, were just being born while Holliday was bringing audiences to their feet midsong on Broadway.

But Hudson holds the distinction of being the only performer who actually gets to sing those numbers, and more, on the bigscreen in Bill Condon’s film version of the musical. The 25-year-old Chicago native with no professional training is making her film debut as Effie.

Her impressive vocal talents are unknown only to the scattershot-few Americans who missed her lauded rendition of Elton John’s “Circle of Life” on the wildly popular Fox TV hit “American Idol.” She may not have walked away with the third-season crown, but securing one of the most coveted movie musical roles ever is one heck of a consolation prize.

Admitting that it was “the music, the music, the music,” that initially drew her to “Dreamgirls,” Hudson says that as she steeped herself in the role she grew to “fall in love” with the vulnerable and sometimes intractable Effie, and found herself as smitten with her acting duties as she had been with singing.

It’s no surprise that the showstopping “I Am Telling You” segment is her favorite moment. She never doubted her ability to sing it, she says, but what gave her the greatest satisfaction was being able to act the scene. “It wasn’t easy, but it was so worth it.”

She assigns major props for this transformation to Condon, “without whose beautiful spirit I would never have gotten through this,” she says, “I would have been too intimidated.”

She cops to being a bit cowed at the first “Dreamgirls” read-through, but who wouldn’t be when the room is populated by such fierce talents as Eddie Murphy, Jamie Foxx and Beyonce Knowles? She credits the support of her “Dreamgirls” family with shoring up her confidence throughout the two-month rehearsal process, “which made the shoot much easier since I’m only comfortable when I know what I’m doing.”

It also helped that the gravity of the undertaking was leavened with healthy moments of fun, many of them provided by the naturally gregarious Foxx, who was always around lifting the company’s spirits during the long shoot days.

“There was never a dull moment with Jamie around,” Hudson beams.

Favorite film of the past five years: ” ‘Ray,’ definitely, hands down.”

Actor who impressed you greatly after working together: “Anika Noni Rose, my co-star in ‘Dreamgirls.’ She is amazing, both vocally and as an actress, so you all get ready.”

Next project: “I’m recording my first album. After that, I would like to do another movie.”