The 50-year-old Glee star said that she first realised when she was playing with her brother as a seven year old.
She told the National Enquirer, 'My brother was switching ears with his transistor radio and I said, 'You can't do that. You can only hear out of one ear.' And he was like, 'No. I hear out of both!'
'I said, 'Mum, I only hear out of one ear'. And we went to the doctor. It's nerve deafness, probably from a very high fever when I was a baby.'
But she said she has managed to work round her disability. 'I shoot the sound into my one good ear,' she said. 'If I think about it, I can straighten it out, but a hearing aid wouldn't even help (that ear) it's stone-cold deaf.'