Listening to Rainbow, Mariah Carey's seventh album, it's clear that the best reason to rock this New Year's will be to celebrate the end of the Mariah decade. Her record sales throughout the '90s have grown to rival those of Elvis and the Beatles, and to many ears the Mariah sound has grown indistinguishable from the endless cosmetics aisles and multiplexes of our postmodern world. But there's no pot of gold at the end of Rainbow. The album strips that sound down to its purest form, cleverly obfuscating Mariah's predictably smarmy lyrics with sonorous mumblings, so that we can clasp Mariah's vocal range to our hearts without having to trouble with the language. Trouble is, "Always be My Baby" is exactly what you'll be expecting after a few minutes of listening, as Rainbow sounds a lot like Butterfly, her previous album. To the album's credit, Jay-Z, Usher, Snoop and Missy Elliott are featured, although Jay-Z seems to be wanting nave Annie-esque samples for counterpoint--not that Mariah sounds particularly world-weary when she sings about her "Heartbreaker" boyfriend. And Rainbow is so mainstream, so generic, that Snoop and Missy Elliott sound like animals in a porcelain party. Your Tupperware and slumber party crowd will do far better to rent The Rainbow Connection. D