How bonkers is Bjork? Having alienated most of her fans with a series of increasingly self-indulgent releases, she's now declared that "instruments are so over" and recorded an album made up almost entirely of vocals. Not just her own, mind - Robert Wyatt, Mike Patton from Faith No More, an Inuit throat singer and the Icelandic Choir all provide the background noise, over which Bjork warbles away in the other-worldly manner that people tend to either love or hate. It all sounds off-puttingly avant-garde, but in practice it's surprisingly conventional - and, thankfully, contains her most impressive songs in years. In its most transcendent moments, in fact, it's a bit like attending a particularly cool cathedral service. Medulla is an album that demands an awful lot of concentration from the listener. It's well worth the effort.