Feline hearing abilities usually wane with age, just like in humans. Felines are usually granted "senior" status at around 12 years old.
Our cats always seem like little babies to us, so it's hard to know when they are actually "seniors." Aside from a tiny -- and pretty cute -- sprinkling of gray around the muzzle in some cats, most times it's practically impossible to tell from the outside. However, cats tend to experience noticeable health-related symptoms of aging -- think hear loss -- at around 12 to 14 years old, although they may appear earlier or later depending on the animal. No set age exists for when cats get age-related hearing loss. It happens when it happens, if it happens, whether your cat is 7 or 17.
Frustratingly, your cat can't just tell you in so many words that she can't hear very well anymore. Because of that, it's up to you to figure out what's going on. Take charge of the situation. Observe your senior cat for any indications that her hearing is going. For instance, cats with hearing problems often seem confused, disoriented and just plain out of it. Your cat might act totally unfazed by unexpected loud sounds, from thunder to dogs barking. She may seem totally unaware of your presence even if you're right next to her. She may even display coordination and balance issues while walking. All of these things point to a cat that is developing hearing loss with age.
If you don't know what you're looking for, figuring out whether your pet may be losing her hearing just by looking at her is next to impossible. However, there are ways to to quickly check before scheduling a veterinary appointment. Examine your cat's hearing by glancing at her ears up-close. If her ears are emitting a yellowish or dark black substance, it could be an indication of hearing loss. Also look out for red ear canals -- another telltale sign of possible deafness.
Even though hearing loss is especially common in seniors, it is indeed possible at any age. If you for any reason suspect that your dear fluff ball is having hearing difficulties, take her to the veterinarian as soon as possible. The sooner you know what is going on, the better. Cats young and old alike can experience deafness due to a variety of medical ailments, including infection and ear mites.