"Ambient" music inspires pretentious poseurs. It can also brilliantly sustain a mood over long stretches, providing a suitable soundtrack to an experience. It often does both simultaneously. Wagner transmutes into Mantovani while Pink Floyd solidifies into Yanni, if you're not careful. Von is the Icelandic group Sigur Rós' debut album just issued in the United States. It's a spare collection of slow-moving pieces far less structured than their subsequent work, suggesting ice caps of the Arctic slowly melting with random ghosts passing through. Wordless (well, maybe Icelandic is spoken, but it doesn't sound like words), the vocals add to the mystique. It's somewhere between Penderecki's Entombment of Christ and the crap that plays while boats sink on the National Geographic channel part put-on, part studio magic.