Keith Sweat, with K-Ci and Jojo and Elvis White

In 1988, R&B's heartthrob roster included deep-voiced crooners like Guy's Aaron Hall and New Edition's Johnny Gill and flutter-voiced falsettos such as the Deele's Babyface. Thrusting himself into the picture was Harlem-born Keith Sweat, whose bizarre, quivering voice resembled the aural offspring of '70s singer Steve Arrington and Jello Biafra. Sweat's vibrato wasn't all that distinguished him from his peers. When the new-jack-swing movement injected hip-hop machismo into the genre, resulting in provocative tracks like Bell Biv Devoe's "Do Me," Sweat became more suppliant. On 1991's New Jack City soundtrack, which unleashed Color Me Badd's "I Wanna Sex You Up," Sweat pleaded his way through "(There You Go) Tellin' Me No Again." Sweat's strategy worked masterfully, with his unorthodox delivery reinforcing his vulnerable lyrics. Ladies loved his mix of sexual confidence and eager sensitivity, and even hard-edged rappers admired his style; respectful Sweat references dot dozens of hip-hop tracks. Fans rejected 2002's upbeat Rebirth, but they'll find signature smoothness on next month's Velvet Room. Once Sweat looks into the crowd and lovingly renders his ballads, spectators will forgive subpar studio efforts, though they might make him beg first.