Mariah Carey / Jennifer Lopez

Charmbracelet (Mosaic/Island) / This Is Me...Then (Epic)

Mariah Carey and Jennifer Lopez are two-of-a-kind polar opposites. Marketed as bronze bombshells, they've crossed freely between black and white pop realms like few other stars. Their bastardized African American music has been partly legitimized, perhaps, by their mixed-race status (Carey is a bit of everything; Lopez is pure Puerto Rican, which is to say she's also a bit of everything). And yet Carey, hailed as our era's most vocally gifted superstar, started blundering right when Lopez, our era's least gifted star, started blooming. If life were a TV movie, these two conceptually opposed albums would correct that "injustice." But it isn't, and they don't.

Lopez's album isn't much of a winner this time. Its soft romantic ballads and obvious old-soul grooves are so timid that they're inevitably a disappointment after the sharp dance hooks of 2000's hugely popular J.Lo. More off-putting still is the disc's shallow show of "realness," especially "Dear Ben," Lopez's embarrassing love letter to fiancé Ben Affleck. The catchiest cuts are straightforward covers or brazen interpolations of light pop standards, but the understated music and lack of promo hype nonetheless manage to free this natural actress from the pressure of following her old roles. As a pleasantly forgettable intermezzo, it leaves you attentive for the next act.

With as much aplomb as possible, Mariah Carey has announced that her next act will be exactly like her first. So where her last couple of flops recast the über-pop diva as a straightforward R&B dolly, Charmbracelet returns to Carey's home turf with humility. From the blubbering opening ballad "Through the Rain" to the light-stepping Eminem dis "Clown" to the brazen retooling of Cam'ron's hit "Oh Boy" as "Boy," the moderately competent songwriting is continuously undermined by the most affected vocal production of Carey's career. Instead of unleashing her usual rockets-red-glare up front, the hapless superstar lays back in a hoarse and breathy high whisper, supported by layers of background overdubs in which her operatic range again soars like a Scud. Almost every song thereby avoids the midrange in which most of us normally speak and sing -- a thoroughly grating and alienating effect. She isn't just Lopez's opposite; she's everybody's.