RAISE YOUR VOICE

[] (One star)

Off-key schmaltz. Running time: 103 minutes. Rated PG (mild vulgarity and profanity). At the Empire, the Lincoln Square, the East 86th Street, others.

JOHN Corbett, the “Sex and the City” hunk who has a thankless role as Hilary Duff’s singing teacher in the treacly “Raise Your Voice,” told reporters at the movie’s press junket he was retiring from acting because he was bored.

That’s a sentiment likely to be shared even by this movie’s target audience of ‘tweens – when they aren’t laughing at the corny plot twists in what amounts to La Duff’s version of “Glitter,” which also lifts shamelessly from “Fame” and a dozen other performing-arts movies, to deadening effect.

Duff shamelessly mugs as Terri, an Arizona teenager who conspires with her mom (Rita Wilson) and sculptor aunt (Rebecca de Mornay) to attend a prestigious summer music program in Los Angeles, despite the wishes of her overprotective, toothpick-chewing dad (David Keith).

Terri lies to her dad and pretends to be staying with her aunt – which is presumably OK, because her attending the program was the last wish of her brother (Jason Ritter, look-alike son of the late John), who died in a car crash just after mailing in her application.

Once at school, Terri must get past her grief to master classical selections (pretty painful to hear) before landing a hunky Brit boyfriend – Oliver James of “What a Girl Wants” – with whom she has a duet in the annual talent show.

Guess who’s in the audience?

Director Sean McNamara – like Duff, a veteran of the Disney channel – treats this like just another direct-to-video project.

He doesn’t seem to have noticed that Duff’s tight tops emphasize her noticeably fluctuating weight from scene to scene – or that her lip-syncing often leaves much to be desired.

“Raise Your Voice” is the kind of overlong, blandly soporific movie that gives you ample opportunity to notice things like that.