In his 20s, English saxophonist John Butcher studied physics and played jazz. After he finished his doctoral thesis on charmed quarks, though, he abandoned both pursuits--and, according to a 1998 interview in Coda magazine, discarded along with them "90 percent of what the saxophone usually does," piecing together a highly individual voice out of the sounds that were left. Now 46, Butcher fashions entire improvisations from sharp squeaks, gruff barks, avian squawks, and ephemeral whistles, mostly on soprano and tenor. He's especially skilled at manipulating multiphonics, the complex, grainy tones produced when two simultaneously sounded pitches interfere with each other. Someone like Dewey Redman or Joe McPhee might use them to climax a solo, but Butcher does something more difficult: he shifts precisely between multiphonics and pure, straight notes. His pieces unfold with a painstaking logic that makes his most alien abstractions as approachable as his carefully drawn melodies. And to further extend his instruments' vocabulary, he's turned to technical enhancement: On "The Step Sequence," a duet with local guitarist John Corbett from the CD Music for Seven Occasions (Meniscus), he sticks a microphone into his saxophone's bell to pick up the thumping and clicking of its keys. And on the astounding Requests and Antisongs (Erstwhile) he submits his playing to Phil Durrant's real-time electronic refractions. But for this concert at the Empty Bottle--also where Butcher recorded the half-hour-long solo on his latest album, the splendid Fixations (14) (Emanem)--he'll play in an acoustic trio with two Chicagoans who appeared on Music on Seven Occasions, cellist Fred Lonberg-Holm and percussionist Michael Zerang. Matana Roberts, a young alto saxophonist who has frequented the Sunday-evening jam sessions at the Velvet Lounge, will open with her own trio. Wednesday, March 21, 10 PM, Empty Bottle, 1035 N. Western; 773-276-3600.