NOW THAT John Travolta has silenced his critics to reestablish himself in the hearts and minds of American moviegoers, there’s still a genre left for him to remaster: music.

Yes, music. Long before he got Shorty, discovered black, talked to dogs, or felt the power of white polyester, the comeback kid was America’s most promising singing sensation. Back in 1976, when he was proud just to be called Welcome Back, Kotter’s sexiest sweathog, Travolta recorded two albums for an old RCA Records affiliate. One ballad, ”Let Her In,” cracked the top 10. It was followed by two more sticky-sweet tunes that made it into the Top 40.

But that’s not the end of his musical legacy. Travolta’s giddy Grease duets with Olivia Newton-John on ”You’re the One That I Want” and ”Summer Nights” helped make the soundtrack one of the best-selling albums of all time. (According to an informal Chicago Tribune poll of DJs, ”Greased Lightnin”’ is among the most requested songs at weddings.) And liner notes for a recently released English import, John Travolta: Greased Lightnin’ (Charly Records, $9.99), go so far as to argue ”Travolta was a star on record before Hollywood beckoned.”

If Meatloaf could revive his half-baked career, couldn’t a fleshier Travolta? Are Quentin Tarantino movies violent? ”We would love a video of Travolta,” says Lee Chesnut, VH1’s vice president of music programming, chuckling at the prospect. ”It wouldn’t matter if the video or song were good or bad, we’d play the hell out of it.” In fact, VH1 did just that with two American Bandstand appearances made by a goofy-looking Travolta for a Bandstand retrospective the channel premiered Jan. 1.

Experts believe the key to Travolta’s musical comeback would be to build on the breezy wise-guy image established in Pulp Fiction and again in Get Shorty. ”So maybe he’s the next Vic Damone. Or maybe he could do a duet with Tony Bennett,” says Jonathan McHugh, an A&R executive at A&M Records. Much like Bennett’s, Travolta’s career now spans many generations. ”He could do a tiki-lounge tour of the States backed by members of Morphine,” says Mike Gitter, an Atlantic Records A&R executive. ”It would be swinging enough for hipsters and groovin’ enough so that your mom would dig it.”

Adds Tim O’Heir, a music producer at Massachusetts’ Fort Apache studio, where Juliana Hatfield records, ”He’s a great singer in the Elvis tradition, with those soothing baritones.”

Unfortunately, the only person not talking about Travolta unplugged is the actor. ”At the present time,” says his spokeswoman, ”John Travolta is concentrating on his feature-film career.” But we’ve heard that song before.