A cat’s sense of hearing is much better than that of a human. A human ear can hear sounds of very low frequency of 20 Hertz to a very high frequency of 20,000 Hertz. Cats’s hearing is about the same on the low end, but they can hear high pitched sounds of up to 100,000 Hertz. Everything about a cat’s ear is designed by nature to aid her in hunting, and that includes the ability swivel her ears. But what is the purpose of those small pockets on the side of your cat’s ear?
Anatomy of the feline ear
Your cat’s ear, just like a human ear, has three main parts: the outer ear, middle ear and inner ear. The outer ear is made up of the pinna, which is the large triangular part, and the ear canal, which normally has few hairs and is white or pink in color. The middle ear is contained in a small bony pocket at the base of the skull and can’t be seen from the outside. The inner ear contains the actual organ of hearing (organ of Corti). This is where sound waves transmitted through the middle ear are converted to nerve impulses that are sent to the brain. The inner ear also contains three small fluid-filled canals set at angles to each other that are responsible for the sense of balance.
As we know, cats are mysterious creatures, and the small pockets on the side of your cat’s ear, also known as “Henry’s Pockets,” are one of those mysteries nobody seems to quite understand. They are a normal part of a cat’s ear anatomy, but seem to have no known function. One theory, according to Wikipedia, is that the pockets aid in the detection of high-pitched sounds by attenuating lower pitches, especially when the ear is angled. So perhaps these pockets help your cat hear the mouse before she can smell or see it.