A couple years ago, the dramatic ascendance of singers like D'Angelo, Erykah Badu, and Angie Stone--all of whom married a love for hip-hop's looped rhythms to an interest in updating the languid, jazz-infused soul of the 70s--prompted the music press to coin the phrase "natural soul." Originally a nod to the artists' nappy hairstyles as much as to their preference for organic, acoustic sounds, that tag has since become nearly useless: thanks to an explosion of new singers, there's now so much stylistic diversity in this musical microcosm--from Macy Gray's grit and sass to Alicia Keys's terse, poppy grooves to Jill Scott's poet-diva charisma--that it makes more sense to take on each performer on her own terms. N'Dambi (aka Chonita Gilbert), a onetime backup singer for Badu, hasn't attracted the kind of mainstream attention those other artists have, but that's a more or less predictable result of her aesthetic choices: on her new double CD, Tunin Up & Cosignin (on her own Cheeky-I imprint), the Dallas native eschews tight, catchy three-minute pop songs in favor of more open-ended arrangements, and often improvises vocally instead of clinging to a fixed melody. For her debut album, Little Lost Girls Blues, the "band" was actually a startlingly convincing studio concoction by producer Madukwu Chinwah, but this time around N'Dambi has enlisted the support of real musicians. While their deep, slinky grooves evoke the hypnotic repetition of hip-hop, N'Dambi's vocals combine the power and throatiness of a gospel belter with the malleability of a jazz singer. She makes frequent use of scat singing and wordless, soaring melismata, and sometimes experiments with enunciation--on "People" she sounds like a cross between a cowgirl with a mouthful of marbles and Billie Holiday. Her consistently resourceful and imaginative performances help make up for the fact that she's not a particularly effective or prolific songwriter; of the new album's two dozen tunes, 11 are rerecordings of material from her debut, in dramatically revamped arrangements--and delivered with lots more self-assurance. N'Dambi and her band have a rapport that's palpable even on disc, and these songs are made to be stretched out live. Friday, November 23, 9 PM, Isaac Hayes, 739 N. Clark; 312-266-2400.