Like an infant whose vocal awareness hasn't yet been funneled into any standard repertoire of language sounds, "voice artist" Lynn Book (with bassist Tatsu Aoki, who keeps up with her like Charlie Haden with Ornette) makes one ponder the long millennia it's taken humanity to evolve such a thing as language. In performance she grunts, squeals, gurgles, and makes sounds simply unnameable, but her emotional range goes for beyond any mere childlike joy in the production of obnoxious mouth noises. Book's highly disciplined "music" suggests a poignant struggle to communicate, from a position of isolation, by turns inchoate and eloquent, joyful and sad. Even while--with only occasionally overbearing theatricality--she moves out to explore the subtleties of this relatively uncharted, yet oddly familiar, sonic terrain, Book (who named one of her recent performance pieces Mouth) is also intent on looking inward at an especially private and sexual part of the body. This is dense, multilayered stuff hitting at many issues at once--and yet somehow it all sort of swings. Sunday, 8 PM, and next Sunday, October 4, 8 and 10 PM, HotHouse, 1565 N. Milwaukee; 235-2334.