The term "electroacoustic" was coined to describe music that blended electronically generated tones and acoustic orchestral sounds, a technique pioneered by composers Iannis Xenakis and Karlheinz Stockhausen. But lately the word has also come to mean the electronic manipulation of acoustic instruments--Evan Parker's Electro-Acoustic Ensemble, for instance, includes a trio of improvisers who "play" the sounds of the other members, proccessing the sax, drums, or strings on the fly and feeding the results back into the music; similar territory has been explored by Burkhard Stangl, Christof Kurzmann, John Butcher, and Phil Durrant. Keenan Lawler, who lives in Louisville, Kentucky, uses real-time digital sampling to distort, elongate, and atomize the bright drones and kaleidoscopic overtones he creates by bowing a National steel guitar. His instrument is usually associated with bluegrass and the blues, but on his self-released CD-R The Ghost of a Plane of Air Lawler makes it sound like distant bagpipes, sluggish voices, and humming power lines. He draws inspiration from the dense, seething drones of Alvin Lucier and Tony Conrad, but his improvisations are less static, fluidly shifting shape and timbre. Lawler has toured throughout the south, both on his own and with guitarist David First, but this show--at which he'll perform solo and with local tabletop guitarist and electronicist Kevin Drumm--is his Chicago debut. First on the bill is a duet between cellist Fred Lonberg-Holm and percussionist Michael Zerang, their first in over a year. Sunday, 7 PM, No Exit, 6970 N. Glenwood; 773-743-3355.