Did you know that...

[zhiva]

...72% of white cats are deaf? They suffer from congenital deafness caused by degeneration of the inner ear, which is associated with blue irides. In study of white cats it was found that the entire organ of Corti degenerated within the first few weeks after birth, however even during these weeks no brain stem responses could be evoked by auditory stimuli, suggesting that these animals had never experienced any auditory sensations.

(from wikipedia)

So that awful white cat of my grandmother could be just deaf.