From a young age, we’re taught the sounds that animals make, yet mystery shrouds the sounds that animals hear. And, in the case of those critters that have no ears to speak of, how it is they can hear any sound at all. Research shows that, no matter how marvellous the human ear, our sense of hearing is far surpassed by many in the animal kingdom. So here’s a look at some of the outstanding auditory capabilities of those with feather, fur, or fins.
When someone has bad eyesight, we declare them ‘blind as a bat,’ and for good reason too. But what bats lack in vision, they make up for in hearing.
Using a technique called echolocation, bats are able to navigate their way around and detect and hunt down prey. Echolocation is a process of emitting ultrasonic squeaks whilst in flight then measuring the time it takes the sound vibration to hit a nearby surface and bounce back. This allows the bat to understand the lay of the land and the location of its next meal.
Interestingly, dolphins also use squeaking and echolocation to hear underwater. They don’t have external ears, but scientists believe the bounce back of sound vibration strikes their lower jawbone which then conducts sound to the middle ear.
While our ears are great for hearing and propping up sunglasses, they don’t do much else beyond that. We’re hard pressed even making them wiggle. Elephant ears, on the other hand, now they’re a feat of nature.
Grand in size and even grander in function, the ears of an elephant endow the animal with an impressive 16-12,000 Hz hearing range. As a result, elephants can hear sounds 20 times lower than our human ears can detect, from the distant rumble of thunder to the low frequency noises constantly emitted by other elephants, up to 6km away. Elephants also use their ears to keep cool with the large surface area and thinness of the ear helping to regulate body temperature. Overachievers or what?
Call them what you will, but pigeons happen to be the best navigators in the world - and it’s all because of their exceptional hearing ability.
While you’re turning up the volume on your voice navigation, pigeons are tuning into a frequency far lower than what can be heard by the human ear. In fact, the average pigeon is able to hear infrasounds as low as 0.5 Hz. Not only does this allow them to detect distant storms, earthquakes, and even volcanoes, but infrasounds provide pigeons with an entire range of navigational tools tantamount to having an inborn radar. They can even pick up on sounds deflected horizontally from hills and mountains so there’s not a chance that scrap of sandwich you dropped went unheard.
Strain with all our might, but the highest frequency audible to humans remains 20 kHz. Now compare this to the 300 kHZ auditory capability of the greater wax moth and you’ll understand why it takes the crown for the best hearing on earth.
This supersonic sense has evolved as a defence mechanism, allowing the moths to pick up the high-pitched calls of bats - their natural predators.
Despite the simplicity of its ears – a pair of eardrums on its flanks that each vibrate four receptor cells – the hearing capability of the greater wax moth is not only unprecedented but so far unmatchable (much to the chagrin of scientists and engineers the world over).
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National Hearing Care blog is our place to explore ideas and themes of interest. For professional audiology advice, please contact your local clinic for a consultation.