Avant-garde woodwind player and Art Ensemble of Chicago member Roscoe Mitchell, now 72 years old, is known for his circular breathing technique. The late Rahsaan Roland Kirk introduced the skill — which allows a musician to play his or her wind instrument via a continuous and uninterrupted stream of air — to jazz in the '60s. During a June 2004 gig at the now-defunct Chicago South Loop club HotHouse, we saw Mitchell play a clarinet, without pausing for a through-the-mouth breath, for what had to be 12 minutes straight. It was completely insane. But the technique is more than just a gimmick, much more. ''For me, it's a tool that lets me extend sonic scenarios even much further,'' says Mitchell, who adds that it took him about a year to learn how to circle-breathe. ''If I can do it continuously and if I want to create really long lines that go on and on and on, I can do that. It's a constant learning process. Sometimes I'll look back at things that I did a long time ago, and now that I can circle-breathe, I can do those in different ways.''