THE DRAKE HOTEL -- "If you're not having fun, the fault lies with you." This announcement is greeted by hearty laughs from the audience, who have been watching musicians improvising with each other for the last 20 minutes or so. It sounds absurd, the spectator bearing the responsibility for his own enjoyment. But Misha Glouberman isn't kidding.

Two hours later, most of the audience stands in front of the stage making unintelligible noises. A slim, pretty girl in a black and red t-shirt sees me pointing to my head and frantically grunting like a Neanderthal. After catching my eye, she approaches and begins gesticulating wildly. I earnestly attempt to follow her directions by varying the pitch and intensity of my grunts. After a minute or so we break it off, giggling. Later on, the audience forms groups of five or six and practice making noises with each other in various combinations, using special cards with markings like "M? (Ear 2)" and "E (Nose 3)." The atmosphere in the room is like a cross between an asylum and the best carnival in the world. Welcome to Room 101 Games' Open Cobra.

Cobra is one of several game pieces devised by New York-based improviser/composer John Zorn. Created in 1984, it uses a complex system of cards and hand signals to form a common language for the players, whose commands are regulated by a conductor figure. Zorn, who is as misanthropic as he is prolific (he famously chastised Václav Havel, Lou Reed and then-US Secretary of State Madeleine Albright for chatting during one of his concerts by telling them to "shut the fuck up and listen to the music you jive-ass motherfuckers"), refuses to publish or explain the rules to Cobra, preferring that the audience should remain ignorant of the system shaping the performance.

Enter Glouberman. A lecture given by Zorn at Harvard aroused Glouberman's already-thriving interest in improvisational games, and in June he and drummer/composer Joe Sorbara jointly presented the world's first "Open Cobra" at The Drake Hotel. Others have played the game without Zorn's involvement, but Glouberman and Sorbara are the first to invite -- make that require -- the audience to participate.

People are welcome to simply watch Round One while Sorbara's Pickle Juice Orchestra demonstrates the original game (which they will also perform Dec. 3 at the ArrayMusic Studio). After the break, they must choose to either participate in the all-vocal, humming/squealing/chattering Round Two or leave -- there are no spectators. Though the crowd thins out significantly, both quitters and stayers seem delighted by the absurdity of it all. In a section dubbed "Cartoon Trades" we spit out rapid-fire snippets of noise ranging from the sublime (ecstatic screams) to the ridiculous (actual quotations from cartoons). Though the ACME anvil of self-consciousness sometimes hovers over the proceedings, it never quite lands squarely on anyone's head.

During one of the many question-and-answer sessions, someone asks the million dollar question: "Is there a point to all of this?"

"What's the point of Beethoven's Fifth?" responds Sorbara without a trace of malice. "To bring a bunch of people together to make music." And to have fun, even if they have to make their own. DAVE MORRIS