Partial deafness can be genetic of come with injury, like an infection, or come from age, in mushroom'kit's case ifmts from hy herself, this is because of cochlear degeneration, this will affect mushroom, by making her alot less receptive to noise, often tilting her head or having to ask cats to repeat themselves, it will also make hearing preadators or their mother calling them more difficult, because theyre hard of hearing. They'll also display hiding responses difficulty to control volume of their voice and lots of ear twitching, they'll get startled more easily and will meow loudly trying to hear themselves
Sources, pet md by chewy, i managed to find the information on there ^^
