Picking the individual contributions of Sierra and Bianca Casady out on CocoRosie’s third record is a little too easy. The controlled, theater-ready voice-the one that seemingly tiptoes up the horn of a Victrola-is Sierra’s. The marble-mouthed chatter, fighting off laughter at every turn? That’s Bianca. But this complimentary quality is at the core of everything CocoRosie does. With Adventures, these Brooklynites have created a record that trades in both gravity and flat-out fun; a good example being the lei-adorned rave-up “Japan,” whose lightheartedness feels free-wheeling and tossed off, until darkness descends and opera vocals swoop in.