"Vanessa Rubin sings with soul." That sentence sounds like a jazz album title from the early 60s. But it makes perfect sense when you learn that during her youth, the Rubin family hi-fi brimmed with records by Dexter Gordon, Cannonball Adderley, and others who exemplified the earthy mid-50s melding of jazz with rhythm and blues. And besides, what better way to describe the undercurrent of sassy funk in Rubin's singing? This expression of soul comes neither from Rubin's material nor from any overt references to R & B. Instead it inhabits the very quality of her voice--warm, salty, a trifle slick; it also lurks in her no-nonsense inflections, which contain just enough street, and in the tiny cool tensions created by her tendency to sing a little behind the beat. (All these elements suggest an updated counterpart to the last of the great jazz divas, Carmen McRae, although Rubin has yet to approach McRae's level of interpretive depth.) Rubin's innate musicianship, along with her childhood admiration for horn players, serves her especially well when it comes to scat-singing; her solo improvisations sound like genuine expression (instead of pro forma hipness) as they quite naturally emerge--rather than pounce--from her arrangements. Tuesday through next Sunday, December 5, Joe Segal's Jazz Showcase, Blackstone Hotel, 636 S. Michigan; 427-4846.