By Dr. Karen Shaw Becker
If you're a cat lover (and even if you're not so much) you know that they're undeniably interesting and even enchanting creatures, with intriguing personalities, qualities, tendencies and characteristics. Felines of every size and "make" have a keen sense of smell, and their eyesight could be described as night vision. But their ears are seldom regarded in the remarkable ways they interact uniquely with their world. Here are nine of them.1
1. Cats have ears with three parts
Like other animals, including lions, leopards, tortoiseshells and tabby cats, these mysterious animals have ears with three parts, including:
• The outer ear, made up of a pinna — the pointed part that we usually refer to as their ears — with the plural of pinnae. The pinna is designed to capture sound waves and funnel them down the ear canal to the middle ear. They're able to move them independently; you'll notice it when they lay their ears down when they're annoyed or perk up when they're listening closely to something.
George Strain, Ph.D., a neuroscientist at Louisiana State University's School of Veterinary Medicine, says cats can actually use their ears like radar, turn them toward the sources of sound and increase their hearing sensitivity by 15 to 20 percent.2
• The middle ear contains both their eardrum and tiny bones known as ossicles, which not only vibrate when sounds are heard but transfer the vibrations to their inner ears, where sensory cells in the Organ of Corti3 respond by moving and bending, in turn sending electrical signals to their brains' auditory nerves for processing.
• The inner ear has what is referred to as a vestibular system, which gives cats their balance and spatial orientation. All these closely connected parts of a cat's ears are also interrelated, which unfortunately means not just their hearing is affected if there's an inner ear infection, but their vestibular system as well, which can make cats tilt their heads or curve their bodies toward the source of the infection.
2. Cats' ears have some anatomical similarities to human ears — and some differences
While cats and humans share some things in common when it comes to ears, one difference is that felines have something called a septum, a bony shelf of sorts, which makes it difficult for veterinarians when cats have middle ear infections. There are essentially two separate compartments, making the source of the problem hard to get to.
3. Cats' pinnae have cutaneous marginal pouches
Luckily, there's another term for cutaneous marginal pouches: Henry's pockets, which look from the outside like little folds of skin that contain slits. While interesting, veterinarians aren't actually sure as yet if these serve any purpose. While the term "Henry's pocket" may be interesting and whimsical, sometimes wisps of fur grow out of them, and the name for these is more whimsical still; cat fanciers call them "ear furnishings."
4. Cats have extremely acute hearing
While most cat owners will say their cat has excellent hearing, they often don't understand just how keen it is. According to Strain, cats hear better than both dogs and people, and in fact have some of the best hearing among all domestic animals. Pet MD notes:
"A cat's hearing range is approximately 45hz to 64khz, compared to 67hz to 45khz in dogs. While the range of human hearing is usually pegged at 20hz to 20khz, Strain says 64hz to 23khz is a better representation."4
Strain explains that such a sharp ability to hear comes in handy for self-preservation when there are predators around and also helps when the cats themselves are stalking prey, because it ups their success rate among a much wider range of prey species, he adds.
5. White cats with blue eyes are prone to congenital deafness
If you have a white cat who has blue eyes (or two different-colored eyes) yes, the odds that the cat is suffering from congenital deafness is higher when compared to other cats. It has to do with genetic anomalies, resulting in the degeneration of some of their most important sensory ear tissues.
More specifically, the same gene that gives them white fur and blue eyes, aka "suppressed pigment cells," is also responsible for the hearing disorder. When these parts don't function correctly, the tissue deteriorates, the sensory cells that are normally used for hearing die and the cat loses its hearing.
6. Cats' ear canals are self-cleaning
In this way, cats' ears are not like human ears: cats' ear canals have a self-cleaning mechanism, and they don't need someone "helping them out" with a cotton swab. To do so could even cause ear problems for cats. As Dr. Christine Cain, dermatology and allergy section chief at the University of Pennsylvania School of Veterinary Medicine, explains:
"They're sensitive creatures and susceptible to developing things like irritant reactions when we put things into their ears. Unless your cat has an ear problem, for which you should go to your veterinarian, I wouldn't do a lot of cleaning at home. Don't try to fix it if it's not broken."5
7. Cats are an altricial species, aka "not ready yet"
When they're born, cats (like dogs) are one animal that, for a time, are for all intents and purposes immobile because all their sensory systems, including their hearing, are working at full capacity. In fact, Strain says their ear canals are sealed and even if they weren't, their auditory systems aren't yet working as well as they will be within several weeks. He adds:
"They respond to sounds as soon as the ear canal opens, and their hearing threshold will get better — that is, they can hear softer and softer sounds — in the several weeks after that."6
8. Feline ear temperature is a stress indicator
When a cat's ears get really warm, it tells you they're feeling a little stressed. It's all part of the physiological changes that take place to generate energy, such as an adrenaline rush. That's another way cats can relate to humans, although, admittedly, due to different sets of stress-inducing criteria.
Here's the kicker: Scientists note that hot ears and other warming trends cats experience under stress may only take place in the right ear — but not the left ear — due to the level of certain hormones the stress releases. Pet MD explains that it could be a reliable indicator of psychological stress.
9. You can test a cat's hearing, but it's tricky
Giving a cat a hearing test may be a little dicey, but it's possible, although it won't necessarily detect unilateral deafness, which has more to do with a cat not responding to noises due to high levels of stress rather than actually being hard of hearing. Behavioral tests to pinpoint hearing difficulties are done by the veterinarian making a noise and watching for a cat's response to it. Strain further explains:
"The most objective test we have available to us is the BAER test, which stands for brainstem auditory evoked response. It's like a TV antennae picking up a signal deep in the brain."7
Tests entail electrodes being placed under the skin on the top of a cat's head and in front of their ears, playing a sound and the electrodes detecting electrical activity in the cat's auditory pathway. A series of peaks in electrode activity indicates the ear heard the noise, while a lack of activity peaks means the ear is likely deaf.
Cats Are More Than Special; They're Designed for Survival
A cat's ears contain those three parts, but they also possess other parts, sensitivities and features that work closely with the other parts in an intricate system. Whether they're cats in the wild or the domestic felines we know and love, every part of a cat is unique, and that's why we love them.