When she was growing up in Lowell, Leah Callahan wanted to be an opera singer. And a rock singer. And maybe even a Tin Pan Alley pop singer, because that was the music she practiced religiously every week with Miss Sullivan, her vocal instructor.

So what did Callahan sing when she grew up? A little of everything. Punk. Cabaret. World music. Jazz. Art rock.

Miss Sullivan would be proud, even if a little confused by it all.

Confused is one thing Callahan herself is definitely not these days. She knows exactly what she wants to sing and she's doing it in a style that's as original as any sung around these parts in years.

Her debut solo album, "Even Sleepers," has an endearingly bent feel to it that's devilish and innocent-sounding all at once. Callahan's delicately precise voice can come across as both otherworldly and earthy within the span of a single song, and the spare arrangements by rock musician Shaun Wolf Wortis highlight influences as disparate as tango, fado and cabaret.

Callahan's next live performance takes place at Jacques Underground, the Bay Village spot that welcomes everyone from female impersonators to regular folk. She'll serve both as a vocalist celebrating the release of her new CD and, in an ongoing role, as emcee for the club's "neo-cabaret" series Raw Deal.

"It's great to be coming full circle," said the Allston resident. "I'm doing things that are more suited to my voice."

Not that singing in punk-rock bands wasn't suitable settings for Callahan - at the time.

"I came from a single-parent working-class family in Lowell and (singing) was discouraged because there was no money in it," she said. "I rebelled and decided I wanted to do music anyway. I was going to go to Berklee College of Music on my own, but I couldn't afford it.

"So I cut off my nose to spite my face and decided to quit music at the ripe old age of 16 or 17. I ended up at UMass-Amherst completely directionless."

Not completely, as it turns out. Before she graduated in 1992, Callahan had absorbed a mountain of music styles, all of which were in her head when she became a member of the local "avant-noise" band Turkish Delight.

After three years of gigs with that group at spots such as the Middle East and T.T. the Bear's, another three with the art band Betwixt and a stint with Butterfield 8, Callahan was ready for a change.

And her new direction is certainly a change.

It took shape after Callahan penned a pair of a cappella songs that she sang for Wortis, who encouraged her to write more. She spent two straight weeks in a friend's house composing and listening to borrowed vinyl records for 12 hours a day - music that ranged from flamenco to '30s Turkish songs and the Bulgarian women's chorus.

The songs that emerged were uncluttered, eclectic and evocative, and ideal acoustic vehicles for her voice.

"I'm not getting paid for this," said Callahan, who has a full- time job with a Boston theater company. "No one's telling me to do this or that. I'm just enjoying myself. It's pure self-expression."

Callahan has been hosting the monthly variety show at Jacques, which to date has featured an ex-funeral director-turned-comedian/ puppeteer, an eco-feminist and a hip-hop poet.

"I usually wear a gown or something really flamboyant. I kind of like that `anything goes' atmosphere. That's why I really enjoy playing at Jacques. We feed off that vibe."

Among the loose collective of musicians who often perform with her are guitarist Wortis, accordion player Suzi Lee and multi- instrumentalist Dinty Childs.

The singer calls her live act both "very vintage-sounding" and "not straightforward cabaret." She adds, "We don't do standards."

Leah Callahan appears Friday at Jacques Underground, 79 Broadway, Boston. 8 p.m. Tickets: $8. Call 617-426-8902.
                                                                                            --Bob Young