Kat Edmonson
aged 26, has one album to her name, and it’s been out for just a few months. She has had no formal training, no big-shot mentor. Instead she has a preternaturally gifted voice, sense of rhythm, and ability to swing. Where other singers her age tend to belt out a tune, she retreats, nearly whispering the lyrics, with a timbre that recalls Blossom Dearie. Comparing Edmonson to Norah Jones and Madeleine Peyroux doesn’t quite work; she’s more jazz-focused than they are, even if her set list is more contemporary than theirs. With an imaginative repertoire that includes jazzy remakes of the Cure’s “Just Like Heaven’’ and the Cardigans’ “Lovefool’’ and updates of such classics as “Angel Eyes’’ and “Just One of Those Things,’’ Edmonson might be the most promising American jazz singer to come along since Cassandra Wilson.

“Jazz is progressive, and it’s alive,’’ she says. “I wanted to make it fresh. I wanted to make it sound like I was recording this music in 2009 and still remain timeless somehow.’’

In an interview from her home in Austin, Texas, Edmonson talks matter-of-factly about her life and career. Her nature is unassuming and modest. She sounds as though she feels genuinely blessed to be singing for a living rather than working at a Starbucks or for a real estate broker, both of which she was doing a few years ago.

Music came to her through osmosis. There were no lessons. Growing up in Houston, she got acquainted with the American songbook through the old records her mother played on the stereo and the old movies she popped into the VCR: musicals with Fred Astaire, Gene Kelly, Danny Kaye, and Bing Crosby. By the time she was 9, she was writing songs.

By high school she was consuming music obsessively, but it wasn’t a career path. After graduation, she moved to South Carolina and enrolled at the College of Charleston, intending to study interior design and furniture design. Still, music beckoned, and she started singing - pop songs, her own compositions - at a blues club there. But the hectic schedule of studying full time, working full time at a coffee shop, and singing at night was taxing. And tuition was growing expensive.

She turned her attention back to Texas, this time to Austin and its thriving music scene. She enrolled in a community college, planning to study during the day and sing at night. “When I was driving home after registration, I heard this song on the radio, a guy singing about not ever going to class in college and always hanging out and singing for his friends,’’ she says. “I laughed and said, I can relate, because it was so much like me. I realized right then I would pull out of school and pursue a music career.’’ She withdrew from college and began looking for work with local bands.

In 2002 she auditioned for “American Idol’’ and wound up in the group of 48 invited to Hollywood, but she was quickly dismissed (“You just don’t look like a star, dog,’’ Randy Jackson told her). She returned to Austin and had a series of jobs: waitress, telemarketer, nanny. She sang at open-mike nights. In June 2005 she found herself at a Monday night jazz jam at an Austin club called the Elephant Room. It was there that she realized jazz was her calling.

Mike Mordecai, a trombonist who’s been running the jazz jam since 1980, remembers the first time Edmonson came in - and recalls pegging her wrong. He assumed she was just another “chick singer,’’ as he puts it. “I’m kind of rolling my eyes,’’ he says. “She was young and cute. We’re like, OK, what do you want to sing? She had a nice voice. She started coming in every week. A few weeks into it, it started becoming apparent that she had something special.’’

The door to a music career was opening, but it wasn’t wide enough. Edmonson needed to find more gigs, so she quit her waitressing job and found 9-to-5 hours with a real estate broker. Soon that became problematic too. “My enthusiasm for the job began waning almost immediately, because I was staying up really late at night to sing,’’ she says. “My boss called me into his office one day; he said I wasn’t the energetic girl he hired. At that moment I realized there was no time to waste.’’ She told her boss he was right, and she quit.

Edmonson has spent the past three to four years singing full-time, mostly in Texas but occasionally elsewhere. She played a few dates in the Northeast in the spring and comes back this way next Sunday for her Tanglewood debut.

The invitation to play Tanglewood came after Dawn Singh, who programs the Tanglewood Jazz Festival, heard her CD, “Take to the Sky,’’ and was struck by her restrained style.

“There’s something about her voice that’s really soothing,’’ Singh says. “There’s also something about her personality, her down-to-earth attitude, that I really like.’’

Edmonson seems to take it all in stride, happy to be doing what she loves, flattered that someone might like her singing. There isn’t a trace of entitlement in her words. She credits her pianist and arranger, Kevin Lovejoy, for making her interpretations of standards and pop songs sound so fresh. She talks about her goals in broad terms, with wide-eyed optimism.

“I want to tour, everywhere I can, all of the world,’’ she says. “I want to play more festivals. I already have ideas for another record. I want to do this for the rest of my life.’’

-Steve Greenlee, The Boston Globe