Sir Purcival's Perfect Pinna
A few weeks ago, I destroyed my cat’s (Sir Purcival) favorite toy in a bid to route a pair of mini electret microphones through a styrofoam head. In a wild attempt at redemption I am dedicating this post to my cat. I’m well aware that I may be entering ‘cat-lady level 1000’ with this, but because I have a passion for all things sound-related and animals, I thought this was an interesting topic to touch on.
Hear or be eaten
Although the human auditory system is a fascinating and complex biological system, we still don’t come close to winning a prize for the keenest ears. Creatures of all shapes and sizes have had to rely on two major factors for survival: finding food and avoiding predation. Animals have been honing these survival skills for millennia and this has led to some remarkable adaptations and improved capabilities, particularly when it comes to hearing abilities.
Cats are certainly no exception to this evolution. They are highly skilled survivalists and are excellent predators, mostly thanks to their acute sense of hearing. The average range of human hearing is between 20Hz-20kHz, whilst studies show that the cat’s hearing range appears to fall between 48Hz –85kHz. Although both cats and humans appear to share a similar sense of hearing on the low end the frequency spectrum, cats certainly trump human hearing capability on the upper end of the spectrum. They hear things ultrasonically and this is all thanks to the refined construction and functionality of their biologically marvelous auditory system.
Pinning it on the Pinna
Like humans, the anatomy of a cat’s ear is broken down into 3 parts consisting of the outer ear, middle ear, and inner ear. The mechanical process in which sound waves are translated into electrical brain impulses is also similar in both humans and cats however, the construction of the cat’s outer ear flap - the pinna - is something to marvel at.
Comparative diagram illustrating the the differences in cat and human ears.
Courtesy of www.icalmpet.com
Unlike humans, a cat’s outer ear consists of 32 muscles, allowing them to independently swivel and position their pinna up to 180 degrees, to pinpoint the precise location of a perceived sound stimulus. They receive all the same binaural time-differentiation cues we do but they also receive directional ‘pinna’ cues. Thanks to their pinna, a cat’s ability to localize sound makes our simple binaural hearing capability look infantile. They have figurative satellite dishes for ears.
Side note: I found a fascinating paper on the way mammals localize sound, if you are an animal-loving, sound-nerd (like me), go have a read here.
There is also no mistaking that cat’s also use their pinna to communicate. Sir Purcival loves to tell me how p*ssed off he is with the dog all time. With his pinnae pulled flat back, he gives the best stink-eye, or rather stink-ear, I have ever seen.
Apart from the pinna, when it comes to the rest of the anatomy of a cat’s ears vs a human’s, here are 3 fundamental differences:
Our ear canal is relatively short - a mere 2.5 cm in length - whereas a cat’s is longer and deeper, thus creating a better funnel in which to carry sound to the eardrum.
A cat has a two-chambered ear drum and we only have a single chambered ear drum
The semicircular canals found in the inner ear are highly developed in cats, giving them their excellent sense of balance. Ours are rudimentary in comparison.
Pinna it to win it
To end, cats hear things that us humans simply can’t, and they can localize sound in a way that makes a 19 capsule Zylia ZM-1 3rd order ambisonics microphone look hypercardiod. And this makes them superior to us (according to the cat, of course).
PS: Below is a concise explanatory video on the way cat’s hear by Cats Protection UK.
Be cool. Because cats are cool. Head on over to the Cats Protection website and see how you can help cat in need today.