Mumble Bore: Sia recites some ambivalent lyrics with comical inarticulateness.

The cover of Sia’s previous album, 2008’s Some People Have Real Problems, showed the former Zero 7 singer clutching a fistful of Magic Markers, apparently having just drawn multicolored lines and a crude heart on her face. We Are Born has less room for such sloppy whimsy. On its cover, Sia’s hair may support a chromatic riot of pipe cleaners shaped more or less into a crown, but her face is adorned with buttons, tiles, and flowers affixed in careful patterns. The message, for those who like messages on their album covers, seems to be this: that if Sia’s going to play with frivolity, then she’s for damn sure going to do so with genuine care. If that seems like a contradiction, then she’s at least chosen the right oxymoronic genre: We Are Born starts off as her most club-minded effort yet. Three of the first four songs suggest one form of disco or another, containing both mechanistic precision and hedonistic release. She’s awfully good at the genre on “Clap Your Hands,” nailing the sharp beat with a bass line borrowed from the Dazz Band. The brief percussion breakdown is still long enough for some enterprising DJ to cut back and forth between copies of it and ride the thing out indefinitely, if DJs still do that sort of thing. Somewhere around the fourth song, “You’ve Changed,” Sia switches styles though not tactics, turning to the dance-oriented wing of New Wave. It’s still a lock-step expression of her playfulness, and it’s never on better display than in the sparkling “Bring Night.” Here she becomes Kelly Clarkson leading the Motels, with muted guitar and hand claps blossoming into warmly processed power chords and an “Oh-oooh-oh-oh-oh” chorus whose meaninglessness never diminishes its preposterous catchiness. The song also benefits from its neat (but probably inadvertent) sidestepping of Sia’s main liability as a singer: her tendency to hold consonants at arm’s length, as if they could go off at any second. “You’ve changed for the better,” she seems to be saying in “You’ve Changed,” but the way she sings it, those last three words sound like “duh d-dut duh du-duh.” (That’s right, even the number of syllables doesn’t match up.) It’s hard to tell whether the end of the key phrase in “Hurting Me Now” is “You don’t even notice” or “You don’t even know it,” and Sia reaches almost comical levels of inarticulateness during the first chorus of “I’m in Here,” on which she mumbles her words into oblivion. All of which is too bad, given how often and how well she plays upbeat music against ambivalent lyrics. It’s when she loses sight of either side of the frivolous/serious dichotomy that the tension dissipates. At its best, We Are Born catches Sia letting loose but still holding on. —March Hirsh