New York ? His singing voice sounds eerily like Billy Joel’s a weary tenor, ragged in the higher registers. His piano playing is almost as splashy as the Piano Man’s.

And six nights a week, he performs more than 20 of Joel’s songs in “Movin’ Out,” the new Broadway musical directed and choreographed by Twyla Tharp.

He’s not Joel, though. His name is Michael Cavanaugh. And he’d like people to remember that.

“I don’t want to just be known as ‘the Billy Joel guy,”‘ Cavanaugh says. “That’s certainly no offense to Billy, because Billy’s my favorite. But there already is a Billy.”

You wouldn’t confuse him for Joel based on appearance alone. Cavanaugh is tall, light-haired and a good two decades younger than the diminutive Joel, whose hair is dark and graying.

“Since age 7, the guy’s been my musical hero as a performer and a writer,” Cavanaugh says.

“But I never wanted to be his imitator. I’m just singing his songs, and obviously I’ll phrase things the way he does that’s the way I’ve always heard it, so that’s the way it’s going to come out.”

Two years ago, Cavanaugh was supporting his wife and 6-year-old son as a bar pianist in New York-New York, a Manhattan-themed casino in Las Vegas. Last February, his manager dropped by the bar, unannounced, with a famous client: the Piano Man himself.

Joel recalls being impressed by Cavanaugh’s act. “He had really good musicianship; he could play a song at the drop of a hat; he had energy; he had pipes,” Joel says.

Landing the job

Joel wasn’t specifically looking for someone to sing his songs in “Movin’ Out” Tharp ultimately made all the casting decisions herself. But one of Joel’s associates, who was also at New York-New York that night, recommended that Tharp audition Cavanaugh for the show.

The audition, combined with Joel’s endorsement, was enough to land Cavanaugh the job.

Since then, Cavanaugh’s professional relationship with Joel has extended past the boundaries of the musical. On the final night of Joel’s recent concert tour with Elton John, Cavanaugh joined his hero on stage at Long Island’s Nassau Coliseum to sing and play one song: “Movin’ Out,” of course.

Joel started the song himself, but after the first verse he surrendered the keyboard to Cavanaugh, who played and belted the lyrics with conviction. Joel faded into the background, shaking a tambourine and dancing with a backup singer.

“I was nervous about how the crowd would react because they paid to see Billy,” says Cavanaugh. “But they knew it was just for one song, and they seemed to enjoy it, so that made me feel great.”

The crowd roared its approval standing, clapping, hollering, cheering him on.

Audiences have been responding with equal enthusiasm to Cavanaugh’s performances in “Movin’ Out.” At a recent performance, his bow received easily the most calamitous applause of the evening.

Besides cheering his fiery performances of Joel’s songs, audiences seem to respond to his stamina.

The two-hour “Movin’ Out,” which follows four friends from high school in the 1960s to the aftermath of the Vietnam War, has practically no dialogue: It is almost entirely singing and dancing.

From the bubblegum-and-bobby-socks nostalgia of the first act through the much darker second act in which the main characters lose themselves in a haze of drinking and casual sex Cavanaugh’s energy never seems to flag. He growls his way through “Shameless,” croons prettily on “She’s Got a Way” and tosses off the devilishly hard piano passages in “Angry Young Man” with apparent ease.

“People ask me if I would consider acting, and I guess I would, but my main love is performing music,” he says.

Primary influences

Cavanaugh has nine months left on his “Movin’ Out” contract; if the show is a hit, he will stay with it at least that long. After that, he plans to compose original music and perhaps perform his songs which he describes as influenced primarily by Joel and the Beatles in nightclubs around New York.

But he worries that fans will think, “nothing but Billy Joel,” he says.

Joel agrees that that’s a valid concern. “It’s hard,” Joel says. “He’s going to get that Billy Joel soundalike thing, all the material is Billy Joel material. And if the show is a hit, is that a good thing for him or not? Who knows? But it could also be a starmaker vehicle.

“I think he’s a talented writer. He’s more of an old-school songwriter in that he uses real chords, he plays a real instrument and he harkens back to another era.”

Cavanaugh has made some contacts at Sony, because the record company is doing the show’s cast album. “They’re great. They’ve been really nice and very complimentary,” he says, before imposing a reality check.

“But then again, I have a deal with them singing Billy Joel songs, and that’s the only deal I have. So we’ll see.”