Riceboy Sleeps is a duo matching Alex Somers with Jonsi Birgisson from the Icelandic band Sigur Rós, which goes a long toward signaling the sound in store. Read: dramatic, haunting, wind-swept, watery, willowy, and all sorts of adjectives that suggest both geology and more cosmic concerns. “Happiness” opens Riceboy Sleeps on a breathtaking note, with what sounds like a violin-licked Sigur Rós backing track left bare and slightly modulated to work on its own as ambient music. Indeed, all of the tracks sound like they could be parts of Sigur Rós songs. But their change of inflection—to function as pieces in and of themselves, as opposed to decorative aspects of something bigger—benefits Birgisson’s otherwise familiar ethereal touch. (And maybe some of Somers’ as well, as he plays too in the bewitching Reykjavik band Parachutes.) Slowly bowed strings mingle with chimes and occasional vocals on highlights “Indian Summer” and the “Boy 1904,” but pretty much all of Riceboy Sleeps stands to mesmerize if met in the right acquiescent mood.