Free jazz has always been underground music, and you can’t get any more subterranean than Test–for years, two of this New York-based quartet’s main venues were the Grand Central and Astor Place subway stations. When they weren’t under the sidewalks, they were playing on them: flutist, trumpeter, and saxist Daniel Carter, drummer Tom Bruno, and multireedist Sabir Mateen, all veteran street musicians, met in 1992 when Mateen staked out a corner two blocks from Carter and Bruno’s regular spot. (Bassist Matthew Heyner joined Test three years later.) These days they play conventional gigs too, but the dense simultaneous solos and ferocious energy of their new album, Live/Test (Eremite), definitely belong to a band used to competing with trains and traffic. Test’s eponymously titled Aum Fidelity CD, recorded in 1998, is slightly more varied. On “Alen’s Flight Preparation” Carter and Mateen’s soaring flute melodies intertwine with the same avian grace Eric Dolphy brought to the instrument, and on “What R U Going 2 Due?!” they drop their horns to belt out a gravel-throated free-form blues. The rhythm section never stays in one gear for long, either: Bruno is just as likely to color the group’s improvisations with cymbal flurries as he is to drive them with insistent rim shots, and Heyner’s centered chordal strums and keening bow work provide as much texture as momentum. This is Test’s Chicago debut. Saturday, 9:30 PM, Velvet Lounge, 21281/2 S. Indiana; 312-791-9050. Bill Meyer