A San Francisco treat: vocalist Madeline Eastman rides out of the west to make her Chicago debut. She always swings and she can scat well enough; but while that alone would seem the goal for many singers, Eastman's greater contribution lies in the tough, contemporary edge she brings to her music. Her naturalistic and unsentimental style lends many of her songs an intriguing, ironic distance: I find it a bit discomfiting, and wholly appropriate to the time in which we live. This stance comes from her actual vocal timbre--worldly and tart, with a slightly flattened affect--and from her off-kilter melodic displacements. And her phrasing, with urgent ahead-of-the-beat glides and the downswooping inflection with which she often ends a phrase, recalls the Chicago saxophone tradition that encompasses Gene Ammons, Von Freeman, and Eddie Harris. None of this should suggest a lack of passion, because Eastman brings plenty of punch to her music--it's just that she refuses to confuse real-world delights with rose-colored romance. In other words, on even love songs and bebop ditties, she sings for adults; she even makes you glad to be one. Thursday, April 29, 8:30 PM, Pops for Champagne, 2934 N. Sheffield; 472-1000. Next Friday, April 30, 9 PM, Green mill, 4802 N. Broadway; 878-5552.