It has only been two years since the last Run-D.M.C. album, but the rap world changes so rapidly that the Queens duo already seems like ancient history. In 1986, Run-D.M.C. was the first rap act to crack the pop Top 10 and the first to score a platinum album, but those breakthroughs have since been superseded by the multi-platinum hits by rappers such as M.C. Hammer and Vanilla Ice, who themselves face newcomers such as Candyman. The raw street language of the early Run-D.M.C. albums now seems tame next to the radical politics of Public Enemy and Boogie Down Productions or the dirty jokes of 2 Live Crew and Big Daddy Kane.

The result is rap's first generation gap. The press release that accompanies the new Run-D.M.C. album, "Back From Hell" (Profile), laments that "the 'rap' that's hitting the pop charts now isn't the 'true to the street, b-boy' style" of the old Run-D.M.C. singles. Instead, the release claims, rap "is threatened by gross commercialization, bastardization and minstrelization." On the other hand, younger fans dismiss Run-D.M.C. as "old school" rappers stuck in the worn-out boasting routine without M.C. Hammer's musical samples, Public Enemy's sonic warfare or 2 Live Crew's stand-up comedy.

"Back From Hell" proves, however, that styles may come and go, but great vocalists are timeless. Rap may dispense with melody for the most part, but rappers are still vocalists; tone and phrasing are as important to Joseph "Run" Simmons and Darryl "D.M.C." McDaniels as they are to Luther Vandross or Anita Baker. Many rappers may sample old James Brown records, but only a handful (Run-D.M.C., Chuck D, L.L. Cool J) can blast out syllables with the gospel roar and funky syncopation of the Godfather of Soul. Rap may boast better songwriters than Run-D.M.C. but no better vocalists, and "Back From Hell" is a triumphant comeback for the Sam & Dave of hip-hop.

Run-D.M.C. has added some new moves for this album. Jam Master Jay's mix is thicker with cross-rhythms and layers of samples; the first single, a state-of-the-city address called "What's It All About," sounds like P-Funk by way of Public Enemy. Two tracks successfully apply the Jamaican dub approach to rapping, and keyboardist Stanley Brown adds '70s funk synth to several tracks (including the 1989 anti-crack hit "Pause") as effectively as Aerosmith once added rock guitar to Run-D.M.C.'s first pop hit, "Walk This Way." The hard-edged social consciousness is balanced by such inspired silliness as "Kick the Frama Lama Lama," which chronicles the exploits of Fred Flintstone. In every setting, Run and D.M.C. belt out their rhymes with a vocal authority that's all too rare in the rap world.

Vanilla Ice: 'To the Extreme' The first rap single to top the pop charts is Vanilla Ice's "Ice Ice Baby," from the album "To the Extreme" (SBK). Ice brings Billy Idol's pinup looks and haughty sneer to rap. That image and the reductive simplicity of his sound must be the keys to his success, for he's shallow and predictable as a writer and thin-toned and stiff as a vocalist.

"Ice Ice Baby" was originally a regional hit in the South for the small Ultra Records label before it was picked up and remixed by SBK. The single is the model for the whole album: Ice's clipped monotone recites his chants backed by little more than a cheesy, high-pitched synth (that sounds like doorbell chimes) and a big, booming bass line (a Miami specialty). "Hooked" (the title tune from the original Ultra album) is typical of the album's casual sexism, while "Play That Funky Music" (the original A-side of the "Ice Ice Baby" single) is one of those rap numbers in which the samples are so much better than the rapping that it's embarrassing.

Big Daddy Kane: 'Taste of Chocolate' On "Who Am I," the first single from "Taste of Chocolate" (Cold Chillin'/Reprise), Big Daddy Kane makes a rare rap confession, admitting that his earlier recordings were motivated by a lust for fame and money. He resolves to dedicate himself to improving the African American self-image and turns the track over to rapper Gamilah Shabazz, Malcolm X's daughter. Unfortunately, the self-image he has in mind is his own, for he spends most of the album comparing his skill with the microphone and his own anatomy to the shortcomings of everyone else.

The biggest problem with "Taste of Chocolate," though, is not the lingering sexism and egomania in Kane's writing. It is his mumbling, eye-glazing delivery. Much of the time he sounds like a sleepy-headed student reading a history report in a first-period class with two spoonfuls of breakfast oatmeal still in his mouth. Kane has often presented himself as the heir of Barry White, whose romantic recitations anticipated rap. When he raps a duet with White on "All of Me," though, the sharp difference between White's bedroom purr and Kane's monotonous murmur is obvious. And when he launches into off-key singing on "Keep 'Em on the Floor," you understand why he sticks to a one-note drone most of the time.

Candyman: 'Ain't No Shame In My Game' One of the most refreshing rap debuts of the year has been Candyman's "Ain't No Shame in My Game" (Epic). This young L.A. rapper (who choreographed Tone Loc's first tour) has a light comic touch reminiscent of Kid 'N Play and Jazzy Jeff & the Fresh Prince. He opens each side of his album with a humorous parody of a TV show and goes on to witty observations on modern romance. His infectious hit single slyly suggests that despite their denials, everyone really wants to jump in bed and start "Knockin' Boots." On the other hand, he also offers an irreverent pro-condom song that advises "Don't Leave Home Without It."

A lot of rappers claim that their macho sexual boasts are meant as jokes, but Candyman is one of the few to communicate that humor in his vocals. There's a lighthearted playfulness in his voice that makes it clear he's just having fun, and his rhymes mock himself as much as they mock his lovers and rivals. He nails the rhythmic accents in his raps without the usual harshness and strain; instead his delivery sounds like friendly, natural bantering. When Candyman and his lover quarrel about who's cheating on whom on "Playin' on Me," and when he and his rival rappers argue about "Who Shakes the Best," the opposing parties seem more concerned with the gamesmanship of the give-and-take than with who wins.