Deafness in cats refers to a feline's inability to hear sound. When a cat can’t hear, they don’t react to noises that are present around them. Deafness in cats can cause the following symptoms: -Not reacting to sounds -Not responding to their name or commands -Behavioral changes, such as hiding -Ear flicking or twitching -Frequent meowing -Easily startled Cats who have lost hearing in only one ear may not show any obvious symptoms of hearing loss. Congenital causes of deafness in cats include the following: -Genetic abnormality: Some kittens have genetic mutations that increase their likelihood of experiencing deafness. White kittens with blue eyes are at a higher risk of deafness for this reason. Some cats are born partially or completely deaf because of a genetic defect; this is called congenital deafness. In most cases of congenital deafness, the deafness is pigment related, and most of these cats have an all-white or mostly white haircoat. These cats are not albino (which is a complete lack of pigment), as they do have color in the irises of their eyes, and they may have color in their skin or in part of their haircoat. It is a myth that every white cat is deaf, or that white cats with blue eyes, green eyes, or one of each are always deaf. ~ As a result of Agate being half deaf, she won't show or have all of the signs. Her ears are often flicking or twitching. She's also easily startled. She also doesn't always react to sounds or her name. However, because of this, she has a bit better vision than a non-deaf cat because she has trouble hearing, she needs to be more aware so her senses are better, which include; smell and sight. But she can also feel vibrations in the ground/water/air easier. The gist of it is that because she has trouble hearing, her other senses are better and she's more sensitive to vibrations. But because of she has trouble hearing, she can't hear whispers, and when being talked to from a distance(like getting called for a clan meeting), the speaker must be louder than usual.
Sites: PetMD, VCA Animal Hospitals