Sometimes, the simplest music is the most affecting. So it goes with PJ Harvey's new studio album, White Chalk, which often feels like a sequel to Björk's Vespertine. Absent are the scorched-earth guitars and feral vocals for which the songwriter is known. Instead, Chalk finds solace and strength in desolation and ascetic arrangements. More specifically, this is largely a piano-and-voice album: Icicles drip from the former instrument on standouts such as "The Devil" and "Dear Darkness," songs whose sparse atmospheres resemble a movie score. (Harvey recently decided to learn how to play piano, which perhaps explains the almost-childlike innocence of the music.) Perhaps most jarring for long-time fans, Harvey stretches her voice to its upper range on Chalk. Instead of the booming brashness and coy sexuality conveyed by past works, Harvey sounds like a fallen angel in mourning. The ethereal effect is reminiscent of Is This Desire?, although the soprano's croons and wordless wails on Chalk rely on the contrast between sounds and silence for emotional impact. This device works well in tandem with the fragile music, although it's a different sort of vulnerability from what listeners are used to hearing from Harvey. Not that it's a bad thing. In fact, Chalk is exquisite and bewitching, an ephemeral collection of tunes that flies by too fast.