After more than a decade of mainstream success and three multi-platinum albums, it’s a little late in the game for Christina Aguilera to still be finding her voice. Outside of her exceptional vocal abilities, Aguilera’s main talent thus far has been absorbing and regurgitating trends with such commitment that she essentially disappears behind a calculated varnish. Not that this is unexpected or even unwise for a pop star of her ilk, but when it’s done with the sort of insincerity and contrivance displayed on Bionic, it comes across less as reinvention than as a desperate bid for relevance. Bionic relies heavily on a cadre of writers and producers, to extremely muddled effect. Two of the most notable collaborations, the M.I.A.-penned “Elastic Love” and the Le Tigre-written/produced “My Girls,” are the album’s most enjoyable tracks, but Aguilera herself is nearly invisible on them, even affecting the respective vocal styles of the tracks’ masterminds. (The deluxe edition contains similar mimicking tracks with Ladytron and Santigold.) The closest thing to a true collaboration on the album is the Sia Furler-penned “You Lost Me,” a ballad that crescendos into the sort of melismatic pyrotechnics Aguilera is best suited to. But the meat of the album is devoted to already-passé electro trash (“Woohoo”) and appallingly unsexy R&B (“Sex For Breakfast”) that ignore Aguilera’s biggest asset—her vocals—in favor of half-assed trend-jumping.