NEW YORK — When Esperanza Spalding plays her upright bass, the bulky instrument extends over her unruly mass of curls by half a foot as she bobs and weaves to complex jazz rhythms. The pairing's a visual mismatch, but there's no doubt she's in command.

"Maybe it looks like I'm working hard, but I'm pretty relaxed," says the lithe, 5-foot-6 (pre-hair) nominee for best new artist at the Feb. 13 Grammy Awards. "I'm conscious of playing with good technique and posture."

And on the strength of her two major-label albums, 2008's Esperanza (instrumental and vocal jazz with elements of Brazilian and hip-hop) and last year's Chamber Music Society (a fusion of contemporary jazz and vocals with chamber music, folk and world music), she has captivated a wide swath of admirers, including collaborators Stevie Wonder and Stanley Clarke, plus President Obama, who invited her to play at the 2009 Nobel Peace Prize ceremonies.

Though her albums inhabit the upper reaches of the contemporary jazz charts, she says, "different kinds of people have been attracted to my music, and I see a broad demographic range in the audiences. People are more open than we think and can still identify heartfelt music when they get a chance to hear it."

Spalding, raised by her mother in a tough Portland., Ore., neighborhood, heard her first heartfelt music at age 4 while watching cellist Yo-Yo Ma perform on Mister Rogers' Neighborhood.

"I said something like this to my mother: 'What is that thing making that sound? ... I want to play that! I want to do that!' "

That epiphany led to violin lessons, immersion in the city's classical world (spiked with stints as a bassist with blues and rock bands), a touring gig backing jazz singer Patti Austin, and a scholarship to the Berklee College of Music in Boston, where she became, at age 20, one of the youngest teachers in its history.

Spalding resists the prodigy label, so fellow musicians express their awe in different terms. "What impresses me most is she is kind of a sponge," says Gil Goldstein, the Grammy-winning jazz pianist/producer who helped arrange and produce Chamber. "She's not finished with learning, which I think is the best quality one can have."

Her ability to sing, play, compose and arrange "makes her a quadruple threat" and enables her to work with artists "as diverse as Prince or Herbie Hancock," he adds. "She's versatile and doesn't have a genre pulling her in one direction. That's rare."

That eclecticism is reflected in the multitude of current projects: She plays upright bass alongside two drummers and a pianist in saxophonist Joe Lovano's Us Five contemporary jazz group. She fronts the seven-piece Chamber Music Society on U.S. and European dates. And she's working with hip-hop artist/producer Q-Tip on her upcoming album, Radio Music Society.

That work presents an entirely different "writing and producing challenge," she says. "I want to take this music that contains the most integral improvised parts of jazz and, without sacrificing those parts, format it in a way that it can be heard on the radio."

"There's a market out there for almost everything," she says. "And I think what people want to hear from me is good music that is sincere and enjoyable. It may be different from what people are expecting, but that's what I'm always striving for."