The world of electroacoustic improv, of which the label Erstwhile has been a major documenter, tends toward understatement (if that's not an overstatement): wide open spaces scattered with lightly touched instruments veiled by sparse electronic scrims. Sounds tend to move at glacial paces, requiring, yet never demanding, close attention. As such, experiments in this sound world tend to be brittle affairs, at times even grating if you don't allow yourself to fully submerge.

Wrapped Islands, however, is a very different affair. The meeting of Viennese sound sculptor Christian Fennesz (heard here on acoustic guitar as well as his usual electronics) with the quartet Polwechsel makes this a virtual big band in a scene that tends to favor solo and duo performance. Having five performers on the session helps to explain the breadth of the sound, but clearly the ensemble was going for something specific. Fennesz, one of the two players credited with 'computer', previously built a disc-length piece from Beach Boys samples. And Beach Boy Brian Wilson's rich sounds hover here as well; Wrapped Islands is gorgeously lush. It's wet and sunny, slow but compelling.

Polwechsel are essentially an acoustic group. Although they all employ electronics and effects, the four (saxophonist John Butcher, Burkhard Stangl on acoustic and electric guitars, Werner Dafeldecker on double bass and acoustic guitar and cellist Michael Moser) don't mask their instrumentation, even if the end result is a thick, tight weave. Sounds of strings and sax undercut the hums and whirs that hold the music together, lending familiar voices to the abstraction. The language might not be easily learned, but here it is beautifully spoken.

As Instrument-driven as they are, Polwechsel aren't particularly melodious. On eh, Stangl affords himself the opportunity to play. His finger-picking on the acoustic guitar speaks in paragraphs rather then brief phrases, and where Polwechsel avoid contrast at any cost, Stangl's guitar clashes with, or is crashed against, Dieb 13's "portable computer" and turntables (including, even, a gramophone). Dieb 13 pushes static intrusions through Stangl's slow, Faheyesque lines.

The occasional shard of melody does slip from the turntables, though most of Dieb 13's work here is given over to static and needle pops and the machine noise of his instrument. But his gramophone does let loose forgotten strands from decades past, pulling his scratchscapes into more familiar, or at least referential, terrain. eh is not music for the masses; in fact, it has barely any mass of its own. But the dialogues contained, while spoken softly, are smart.