Over the last half century composers like Helmut Lachenmann and Mauricio Kagel have helped knock down the walls between European art music and improvisation, but this doesn’t mean just anyone can pass freely from one territory to the other. Last week I saw the Kairos Quartet, a German string quartet, perform an improvised piece with the Korean komungo player Jin Hi Kim, and it couldn’t have been stiffer or more forced; the string players trotted out various extended techniques seemingly without any intuition or sense of purpose. Viola and violin player Mary Oliver is one of the rare musicians who’s genuinely proficient in both contexts; she’s premiered difficult works by Xenakis, Cage, and Feldman, but she’s also a crucial member of Amsterdam’s freewheeling ICP Orchestra, which takes composed material and opens it up to relentless, incisive improvisation. Her lone solo recording, Witchfiddle (ICP, 2001), is a series of succinct improv pieces on viola and violin, plus one on hardanger fiddle, a Norwegian instrument with a set of four or five drone strings beneath the fingerboard in addition to the usual strings above it. Oliver’s a terrific melodic improviser, but here she focuses on sound and scale. The album is packed with exaggerated dynamics and weird harmony drawn from contemporary classical music; she’ll sing along wordlessly with her jagged lines or strip them down to whispery string noise and mouselike squeaks. She’ll be joined by reedist Guillermo Gregorio, cellist Fred Lonberg-Holm, and vibist Jason Adasiewicz. Wednesday, February 4, 9:30 PM, Empty Bottle, 1035 N. Western; 773-276-3600.

Art accompanying story in printed newspaper (not available in this archive): photo/Michael Jackson.