Although her flamboyant outfits may 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 in which beatboxing and throat-singing replaced traditional instrumentation felt too gimmicky and academic, and lacked the mischief that marked her previous pop experiments. Thankfully, Björk's gleeful sense of adventure is back on Volta, perhaps thanks to her rediscovery of rhythm. Collaborators such as Timbaland, Lightning Bolt's Brian Chippendale, the African band Konono N1 and a 10-piece Icelandic brass choir make Volta's songs leap alive, from the going-to-battle anxiety of the cinematic, marching "Vertebrae by Vertebrae," to fireworks-esque programming on a triumphant "Wanderlust," and the outer-space-drum-circle driving the bumpy carousel-whirl "Earth Intruders." The slow-burning highlight "Declare Independence" sounds downright dangerous, with bleating beats and thundering synths short-circuiting around Björk as she screams, with more unabashed emotion than she's let loose in years, "Raise your flag! Declare independence! Don't let them do that to you!" Still, those hoping for a carbon copy of Post or Homogenic will be disappointed. Volta's songs are as ornate but lack brevity and a willingness to conform to traditional pop structure meaning that some songs tend to run too long, or simply are as ephemeral as a melting icicle. But the big difference is that Björk seems to feel completely comfortable in her creative skin on Volta, nonchalance that allows her beautiful quirkiness to burst forth joyfully.