While her flamboyant outfits might never be polite, Björk's last few albums certainly were. The ice-crystal percussion and melodies on Vespertine were stunning but mannered, like an immaculately decorated parlor, while the nearly a cappella Medulla -- an album on which beatboxing and throat-singing replaced traditional instrumentation -- felt too gimmicky and academic, and lacked the mischief that marked the singer's previous pop experiments. Thankfully, Björk's gleeful sense of adventure is back on her latest, Volta, perhaps thanks to her rediscovery of rhythm. Collaborators such as Timbaland, Lightning Bolt's Brian Chippendale, the African band Konono No1 and a ten-piece Icelandic brass choir make Volta's songs leap to life. Still, those hoping for a carbon copy of Post or Homogenic will be somewhat disappointed: Volta's songs are equally ornate, but in general lack brevity and a willingness to conform to traditional pop structure. While some songs run too long, some are as ephemeral as a melting icicle. The big difference, though, is that Björk seems to feel completely comfortable in her skin here, displaying a nonchalance that allows her beautiful quirkiness to burst forth joyfully.