Few saxophonists who've emerged in the past few decades can match the technical, improvisational, and compositional brilliance of Edward Wilkerson. Unfortunately Wilkerson's made it tough for listeners to become aware of his vast talent. First, he's stayed in Chicago, whereas most jazz players intent on making a career head to New York. Second, he's been incredibly stingy with his releases--until this week, Last Option, an album from 2000 by his long-running group 8 Bold Souls, remained his most recent. He's finally back, with a new collective quartet called Frequency, which is releasing a self-titled debut on Thrill Jockey. Joined by the magnificent flutist Nicole Mitchell, bassist Harrison Bankhead, and drummer Avreeayl Ra, Wilkerson loosens the compositional reins (he's the sole writer on only one of the nine tracks) and delves much deeper into free improv than he has on any previous recording. The flute's soft timbre often leads to ruminative, spacious exercises--while Ra's "Satya" peaks in some furious ensemble improvising, much of the piece consists of Wilkerson and Mitchell snaking around one another in breathy, lyric lines, accompanied by gentle kalimba and bells. These players have worked together for years, and you can hear it in the relaxed, stunningly empathetic performances. Tue 8/29, 9:30 PM, Empty Bottle, 1035 N. Western, 773-276-3600 or 866-468-3401, $8.