Since forming Radian in Vienna back in 1996, Martin Brandlmayr, John Norman, and Stephan Nemeth have been recording fascinating puzzles — those sliding-square types broken up over a grid you hear rather than see. The puzzles wouldn't be so fascinating if all the pieces were present, but Radian plays up on the mystery that technology permits. With their first domestic full-length, rec.extern, the trio members (along with visiting Thrill Jockey godfather John McEntire) have welded together 40 minutes of ornate electro-acoustic white noise, grey noise, floating noise, hydraulic noise, and any other nondescript noise they can sample on their computers. Not to be confused with labelmates Oval, who more or less "play" clusters of skipping compact discs, Radian rounds out its glitch symphonies with a live set of vibes, bass, drums, and synth. The results convey a bit more soul, but the heavy processing can't be ignored. The songs "Nahfeld" and "Kilvo" follow a similar flight path — terrifyingly crisp and cold mechanics mingle with vibes in suspended animation, while waves of bass pedal and bowed glass slither around acoustic drums that blister up with distortion. Compositionally, the momentum of both comes to a complete halt more than once, and it's debatable as to whether this creates tension or dissipates it. "Jet" shuffles with a good balance between acoustic and static; it's one of the only tracks that feels like the live music is fueling the electronic sputtering rather than the other way around (McEntires production work with Tortoise might seem most evident here). Next, "Bioadapter"'s shortwave radio samples play Pong with each other, while Brandlmayr's drum kit punctures holes in the scorched tin foil that listeners might think they're chewing. The production eases back to "Unje," an unsettling meditation in hums and revolving binary code. "Etage 3/Flur" takes cymbals, cans, and gongs through deeply filtered layers of hiss — the equivalent of a dialogue between Javanese gamelan and a snowstorm with an on/off switch. "Ulan" flutters in and out of acoustic spaces; a hollow moth alternates between a real and virtual light bulb while heavily plucked strings and tapped skins fall out like flakes of rust. Lastly, "Elot" is ambient music composed from straight feedback, and the result is a gently receding shoreline of electromagnetics. Radian certainly holds listeners' attention, but it's not quite clear what the group is saying. The frequent spray of digital hailstones either obscures the meaning or strains to become the meaning itself. Regardless, there's no denying rec.extern is a puzzle that begs to be solved, like finishing an acceptance speech with the word "and."