Deafness in odd-eyed white cats

There is a common misconception that all odd-eyed white cats are born deaf in one ear. This is not true, as about 60 - 70% of odd-eyed white cats can hear.[4] About 10 - 20% of normal-eyed white cats are born deaf or become deaf as part of the feline aging process. [4] White cats with one or two blue eyes do, however, have a higher incidence of genetic deafness, with the white gene occasionally causing the degeneration of the cochlea, beginning a few days after birth.

Source : http://en.wikipedia.org/wiki/Odd-eyed_cat