, now in its 12th year, is such a sturdy Baltimore institution is that it drops the most unpredictable music possible into a consistent but not confining structure that allows for growth and freedom, but is at the same time strangely comfortable and ritualistic. And one of the festival's little traditions is opening each of the five Theatre Project concerts with a solo set by one of the invited performers. This year the Saturday night concert shuffled the solo performer, British guitarist Gary Smith, to the second set. That meant Saturday night's proceedings began, against the grain of High Zero tradition, with a group set. And it was a good one, with local Michael Muniak and Istanbul's Tuna Pase toying with feedback and laptop effects, respectively, while Karen Borca's bassoon, Hans Koch's bass clarinet, and Liz Meredith's viola provided more traditional instrumentation. One of the wonders of High Zero is the way the players appear to tap into a mindmeld and feel out an ending for each improvisation at about the same time. But now and again, especially in the larger groups, the players have different ideas about how and when to let the piece wind down. And on this occasion, Borca and Muniak appeared to be competing to have the last word, his hissing feedback and her melodic clusters of notes dueling by themselves for a few minutes while the other three musicians quietly put down their instruments and watched. Soloist Gary Smith is the kind of talent that High Zero is best at spotlighting: He's been honing an utterly unique style of guitar playing since the late 1970s, and now he has a nice long stretch of time to show you what he can do. And what he can do is hard to describe, treating the whole instrument as a kind of conduit for sound, sliding his hands up and down the strings in opposite directions for a kind of double slide guitar effect, tickling the strings and making sounds that would seem impossible without a big rack of pedal effects. But it is possible, because Smith simply had the guitar plugged into a big amp and turned up really loud so you could hear every little motion of his hands. The second group, a trio of cello, violin, and electronics, yielded some great moments, but it wasn't quite as memorable as the two sets that ended the night. The highlight of the third group was Tomoko Sauvage, a Japanese musician currently living in Paris, whose invented instrument "waterbowls" consisted of porcelain bowls filled with water and hooked up to microphones and electronic effects. Every year at High Zero, there's at least one truly novel, fascinating invention on display, and this year it was Sauvage's, although the other musicians in her group often made a bit more noise. The most noise of the night, however, came from the finale, when Smith returned as part of a trio with Mexico's Juanjosè Rivas bending circuits and New York's Shayna Dunkelman on drums. High Zero often defies the conventional wisdom that experimental music tends to feature a wealth of ear-bleeding noise; in fact, things at the festival sometimes get almost too quiet and polite. So it was a visceral thrill for the Saturday night concert to end with the trio's aggressive squall of sound, with Dunkelman providing most of the energy and volume and Smith and Rivas gamely providing some of their own.