When listening to Icelandic postrock outfit Sigur Ros, it's easy to conjure up romantic images of their homeland: frosted clouds framing a cobalt sky, ice monoliths frozen stoically over ancient lava plains, muffled blasts of the geothermal powerhouse deep below. These postcard shots may have held no influence over the foursome from Reykjavik, but their music is undeniably as blue, blissful and baffling as the landscape.

Sigur Ros ("Victory Rose" in Icelandic) play experimental chamber-rock with slow-burning intensity and dense, cavernous atmospherics. Amid the minimal drumming and cathedral organ, vocalist Jon Thor Birgisson pulls a cello bow across his electric guitar while vocal effects flutter around a doleful piano. When Birgisson sings, his mesmerizing falsetto sounds like something between a choirboy and a very, very lonely whale. Although they are often tagged as the next Radiohead, it was the supergroup's vocalist, Thom Yorke, who said Sigur Ros' earlier work laid the groundwork for the lugubrious analog purr "Kid-A."

Sigur Ros' latest release is somewhat confounding at first glance. Both disk and case are almost completely devoid of writing, and all eight tracks are untitled and sung in "Hopelandic" -- a language of their own creation. The name of the disk? "( )" That's right -- two parentheses.

Beneath the ostentatious packaging is an album of naked, aural emotion that rings clear across the tundra. Where their last album, "Agaetis Byrjun," was a bejeweled talisman of surreal sampling, backtracked cherubic voices and reverb from the edge of the earth, "( )" follows a simpler format, utilizing the organ and piano more than strings. Their melancholic approach reaches almost sepulchral levels here. And like the geysers that pockmark the land of their birth, the album gurgles and builds until the final track, where the emotive pressure finally propels them skyward in a final, cathartic release.