"He gave a solo performance, in which he set up contact microphones to his body and amplified his heartbeat," said Blake-Plock, a local musician and an organizer of this year's 14th annual celebration of experimental improvised music.
"It was," he said, "a completely mind-bending experience for the audience."
It was also pretty much par for the course for High Zero, which, since 1999, has attracted artists from all over the world to make music spontaneously, without any planning whatsoever. The result is four concerts of free-form musicianship with no rules, no boundaries, no preconceptions -- music where the audience's enjoyment can stem as much from the risk as the result.
"It's like getting on a tightrope for the first time, and the tightrope is 90 feet up," Blake-Plock said.
And there's no safety net?
"Exactly," he said.
In a world of carefully crafted four-minute pop songs, where orchestras are graded on the precision with which they play and even voices can be made perfect electronically, such determined mayhem seems out of place. There's no such thing as audiences screaming out song titles at High Zero, Blake-Plock said. Therein lies much of the festival's appeal.
"Part of the experience is anything can happen, and sometimes it does," he said. "It's kind of like walking into a sculptor's studio and watching them for a few hours, seeing what they do. By the end, you see the result. But you've had the opportunity to watch the entire process."
What, exactly, does that process entail? Although each of the festival's four concerts begins with a solo appearance -- Lebanese trumpeter Mazen Kerbaj tonight, for instance -- most performances bring together musicians in groups of two to six. No words are spoken, no pre-arranged notes start things off. Essentially, the music starts to flow when it starts to flow, and it heads wherever it heads.
"We will not make any apologies -- the music itself can be very demanding," said Blake-Plock, who is on the bill at High Zero, working with stringed instruments and manipulated recordings. "At the same time, I think we have a lot of respect for our audience and believe that they really want to see something that they've never seen before."
The possibilities seem endless. While one performance will feature a fairly conventional-sounding lineup of bass clarinet, piano, saxophone and drums, another will combine electronics, drums, toys, a flute and the all-encompassing "miscellany." Most times, even the musicians aren't sure where the music will take them and their audience.
The collaborative performances generally last about 45 minutes.
"They come onstage, and oftentimes the first note you hear is literally their introduction to one another," Blake-Plock said. "There is no conversation at all. Often, the musicians are literally meeting for the first time when they walk onstage. ... These artists are literally creating something new, with no rules, right in front of the audience."
As befits the spontaneous nature of the performances, the results can be uneven. When the musicians mesh, the results can be intoxicating, delivered with wit, enthusiasm and verve. But sometimes, Blake-Plock acknowledges, the sounds are more cacophonous than melodic. Which isn't necessarily a bad thing, he hastens to add.
"For some people, [the highlight] is that moment that was completely unexpected, when everything goes so perfectly right -- the precise cymbal crash or the unexpected piano roll," he said. But other times, there's "a kind of chaos ... that in and of itself can be illuminating."
High Zero is also proudly eclectic. A performers is as likely to be a classically trained flutist as a guitar player in a punk band, Blake-Plock said. "There's really a broad range," he noted.
And the innovation doesn't stop with the performance. Sometimes, the instruments themselves are as new as the music. Among this year's guests is San Francisco's Tom Nunn, who's been creating and performing on his own musical instruments since 1976.
"Not only are you getting the experience of this new music being created in front of you," Blake-Plock said, "but you're also getting the experience of hearing sounds that you might never have heard before in a jazz club or a rock club or a traditional concert hall."
If you go
The 14th High Zero Festival of Experimental Improvised Music runs through Sept. 23 at the Theatre Project, 45 W. Preston St. Tickets are $13 per concert, $40 for a festival pass. Information: 410-752-8558 or highzero.org