Back then, she would listen to the greats — Ella Fitzgerald comes most readily to mind — on her way to these gigs, “just to absorb them in a way. I knew I would never sound like them. You can emulate the great people because you’re you, and it’s never going to sound like that. [But] it gives you a new place to go in your vocabulary.”

Today’s theater lovers likely listen just as closely to soundtracks featuring Menzel’s insta-iconic pipes. Surely you’d know her if you heard her belting in her breakout Broadway role as Maureen in “Rent” (“MOO with me! Come on, sir! Moo, moooooo, MOOOO!”) or her voice climbing octaves like Spiderman scaling skyscrapers in her green-faced turn as Elphaba in “Wicked,” or if you caught her on “Glee” playing the birth mother of Rachel Berry (Menzel doppelganger Lea Michele) and dueting with Michele on Lady Gaga’s “Poker Face.” Soon she’ll be heard as the voice of the titular character in Disney’s upcoming animated feature, “The Snow Queen,” based on the Hans Christian Andersen fairy tale of the same name.

“An Evening with Idina Menzel” will bring the star to Wolf Trap for just one night. Menzel will be performing with the National Symphony Orchestra, and she will be glammed out for the occasion from head to ankle.

Just no shoes.

“Honestly, I always like to perform barefoot, and I was choosing not to [on tour last year] because I was with all these symphonies, because I thought I had to dress up more,” said Menzel. “And one day I had no choice. I was traveling with my little boy,” her 2-year old son. “My back hurt from carrying the stroller and the car seat, and I thought: there was no way I could perform in heels. So I threw them off and performed barefoot, and it was the best show I ever had.”

Like many a woman who swaps stilettos for flip-flops, “I just realized it was so silly.”

Before you ask: yes, she’ll sing “Defying Gravity,” her character’s Act One-closing anthem from “Wicked.” “[It’s] something people want to hear as dramatically and passionately as they can,” she said. “I think that people want to be taken back to that moment when my character was levitated above the stage.”