Jane Horrocks is one spooky lady.

As the title character in Little Voice, the British import that's been hailed as this year's Shine, Horrocks sits hunched over in mute misery, listening endlessly to recordings of American torch singers in her drab, Northern England room. But then, after almost half an hour of suffering in silence, she opens her mouth to sing, and becomes Judy Garland, with the same creaks, cadences, and heartache. As a girl held prisoner by shyness but exploited by her greedy mother for her oddball talent, Horrocks also delivers haunting, dead-on imitations of Shirley Bassey, Marilyn Monroe, Marlene Dietrich, and even the Munchkins from The Wizard of Oz. It's a performance that makes you want to escort Horrocks, 34, either into a mental ward or onto Oscar's podium.

The film's distributor, Miramax, is hoping for the latter and is pushing Horrocks as a possible Best Actress candidate. She's surrounded by some fine thespians: Brenda Blethyn -- an Oscar nominee for 1996's Secrets & Lies -- as Little Voice's treacherous mother; Oscar winner Michael Caine as a skeevy, gold-bedecked agent who wants to make the girl a star; and Ewan McGregor as her shy suitor. But it's Horrocks' nearly speechless part that has critics talking.

Little Voice began in England as The Rise and Fall of Little Voice, a 1992 play written for Horrocks by Jim Cartwright, who first heard her impressions when she starred in his 1987 play, Road. After Little Voice's acclaimed eight-month run, Horrocks declined the invitation to follow the play to New York, turning her attention to television (playing the aptly named Bubble for two years on Absolutely Fabulous) and back to the stage (before director Sam Mendes revived Cabaret on Broadway, he cast her as Sally Bowles in his acclaimed London production). When Brassed Off director Mark Herman approached Horrocks about reprising Little Voice on screen, she was as reluctant as the character.

''I needed reinspiring,'' admits the actress, who is an elfin beauty -- and six months pregnant. (She and her partner, screenwriter Nick Vivian, also have a 19-month-old son, Dylan.) ''I was very satisfied with the first version, and I needed a reason to revisit the part.''

When Herman offered Horrocks a vocal coach to help hone her impressions, the perfectionist finally agreed. ''She'd play the recordings of what she was doing 100 times between takes,'' says Herman, who calls Horrocks' precision ''scary. Her impression isn't just Judy Garland, it's an impersonation of one specific recording.'' Even so, Horrocks wasn't without humor: ''She 'did' Brenda Blethyn,'' says Herman, ''I think if we'd gone into the 10th week of shooting, she would have started to do me, so I decided to wrap.''

Horrocks, who attended the Royal Academy of Dramatic Art with Ralph Fiennes and won a 1991 Los Angeles Film Critics award for her performance in Mike Leigh's Life is Sweet, insists her methodology doesn't extend far off the set. ''I'm not ambitious,'' she says. ''I've decided I like doing one job a year. [The idea of being famous] is something that might be quite imposing and crash into your life somewhat. It's quite frightening.''