Apparently, the best thing Mariah Carey can do to put her career back on track is to cover Def Leppard. The catchiest cut on Carey’s eighth album, Charmbracelet, is a fascinatingly overblown orchestral remake of “Bringin’ on the Heartbreak.” The rest of the album is strangely muddy: On songs such as “Yours,” Carey’s lead vocals blend into choruses of overdubbed Mariahs cooing overlapping phrases. Circling these are choirs of more Mariahs singing harmonies and countermelodies. Topping it off are generous sprinklings of the singer’s patented birdcalls (on “You Had Your Chance”), wails, sighs and whispers. The mostly skeletal musical instrumentation is insignificant: Charmbracelet is nearly wall-to-wall Mariah. Tempos plod, and hooks are few. Carey needs bold songs that help her use the power and range for which she is famous. Charmbracelet is like a stream of watercolors that bleed into a puddle of brown.