I often listen to parts of concerts with my eyes closed, the better to focus on the sounds rather than the onstage flash. It's not that flash isn't a valid part of the entertainment experience, but it's surprising how you hear a concert differently sans visual distractions.

That's what everyone has to do at the Third Angle New Music concerts this week. Taking place at the OMSI Planetarium as part of the Time-Based Art Festival, the score for the program’s only piece—contemporary Austrian composer Georg Haas's third string quartet—explicitly requires that it be played in darkness by four musicians scattered at opposite sides of the room.

That's about as prescriptive as the score gets, however, as it leaves much open to the performers' interpretation. The instructions provide 18 "situations" that allow any of the musicians to invite the others to play a certain sequence, and once the invitation is accepted, they follow a specified sequence of chord changes and other musical elements that leave some room for improvisation, though not nearly as much as jazz does. With all that focus on sound rather than on vision, how would Haas' quartet hold up?

The show opened with a darkness test to make sure no one would freak out, and emergency instructions (clap twice!) for anyone who did or otherwise needed to leave. (No one did.) This information was gracefully presented by Third Angle’s artistic director and violinist Ron Blessinger, who also concisely and engagingly explained how the piece we were about to hear actually worked.

This turned out to be a smart idea, because, as with so many of the so-called “process” works so beloved of post-World War II modernist artists and composers (like those of the Fluxus movement), most of the interest in Haas’ string quartet lies not in its actual substance, which turned out to be a little too thin for its length, but rather in how it works. You could say that about a lot of TBA’s conceptual pieces. Sometimes that’s enough. Usually not.

But unlike many modernist pieces, the quartet did actually evoke feelings as well as intellectual interest. The main feeling was surprise. What would the musicians do next? What sounds might emerge from the darkness? When Haas kept us guessing, the piece worked well. Primed by Blessinger’s explanation, it was easy to hear how musicians issued and responded to invitations—to follow their musical conversation, which proved pretty interesting.

But, like so many other works in this vein, the quartet is really just a series of musical "gestures," and if you've followed much avant-garde music (or spooky old movie soundtracks), you've heard a lot of them before: the creaky viola like a coffin opening; the rising or falling plucked string patterns, the swooping cello lines. Early on, you could even predict what would happen after each invitation was accepted. And when the music became predictable, with no real development or other melodic or rhythmic interest, my mind started to wander. Sometimes it lighted on ambient noise, like suppressed (or not) coughs, seat squeaks and the worst-timed case of hiccups of the year.

Nevertheless, the quartet offered moments of real beauty, startling spacey effects that really made me pay attention to the rare moments of conventional beauty—a pulse here, harmony there, especially in the musical quotation from the great and homicidal Renaissance composer Gesualdo—in the way American minimalism (which this piece otherwise resembles not at all) can do. The playing—so exposed in this tense environment—was immaculate and gripping. Moments of wandering aside, it's an audio(non)visual experience you'll remember longer than the music itself. There's one performance left at midnight Thursday, and it's worth catching.

SEE IT: Third Angle is at the OMSI Planetarium, 1945 SE Water Ave. Midnight Thursday, Sept. 26. $30. More info here.