Esperanza Spalding

Esperanza Spalding, who set legions of tweenyboppers a-howl by beating out Justin Bieber for the Best New Artist Grammy, is one of Greenwich Village's best-kept secrets.

A jazz composer with an angelic soprano voice who plays an upright bass, she mixes neosoul, bossa nova and funk into her jazz grooves.

Spalding's heritage is as exotic as her music: She was raised in Portland, Oregon, by a single mom and calls herself a mixture of black American, Welsh, Latino and Native American. She sings in English, Spanish and Portuguese.

"She's the real deal. She's not candy. She doesn't just look good and have a team of producers behind her. This is a real musician," said Tommy Igoe, the virtuoso drummer who leads the Birdland Big Band on 44th St.

"Seeing a woman playing an acoustic bass is not something you see all the time, and to see her sing and play the bass - I can't tell you what a unique and amazing combination that is. We see one of these come along only once in a while, someone with such talent that they can cross over into the pop culture."

Spalding, 25, is the first jazz singer to ever win the new artist award.

"I certainly did not expect to even be considered for that type of nomination," she said yesterday on her website. "Me being a little old jazz musician and everything."

While she may be unknown to Bieber's fans - who flooded Twitter with spluttering outrage and vandalized her Wikipedia page - Spalding is a star in the jazz world who has been garnering praise from the likes of Stevie Wonder and Herbie Hancock for years.

She recently toured with Prince, and President Obama chose her to perform when he accepted the Nobel Peace Prize in 2009. Spalding says she first fell in love with music when she watched classical cellist Yo-Yo Ma perform on "Mister Rogers' Neighborhood" when she was 4. By the following year, she had learned the violin and was playing with a chamber music society.

She played oboe and clarinet in high school before discovering the bass, and, at the tender age of 20, became the youngest-ever professor at the renowned Berklee College of Music in Boston.

Her 2008 recording "Esperanza" sat atop Billboard's contemporary jazz list for 70 weeks and her "Chamber Music Society" went No. 1 last month.

Grammy-winning bassist Christian McBride defended Esperanza against the bellicose Bieberites.

"It's refreshing that someone who's so serious about the art and science of music won such a coveted award," he said. "As far as her detractors go, there's an old saying: 'When you're on top, someone's always trying to knock you down.'"

Igoe had a challenge for the boiling Bieberites: "Let's all meet back here in 20 years, and we'll see who's still doing it."