In what is likely to be the high point of New Music Chicago's Spring Festival '89, sensation Eric Mandat will play an evening of his remarkable compositions for clarinet. A New Music Chicago jury discovered Mandat's unique artistry among some 400 scores, and quite a find it is. A resident of Carbondale, where he teaches at Southern Illinois University, Mandat is exploring new worlds for the clarinet with a unique combination of virtuosity and a creative use of multiphonics. But the interesting thing about Mandat isn't so much his bag of tricks as how he uses them to create highly personal and expressive compositions that, despite their being written for a solo instrument, have dense textures and are loaded with musical meaning. Thursday, 5:30 PM, 2nd floor theater, Public Library Cultural Center, 78 E. Washington; 477-1379.