How do different animals hear?

Did you know that, on average, humans can detect sounds in a frequency range between 20 Hertz (low frequency) and 20,000 Hertz (high frequency)? Interestingly, infants hear frequencies even slightly higher than 20,000 Hz but lose some of this high-frequency sensitivity as they get older. Although we can detect sounds in a relatively wide range, you will see that this range is actually quite narrow compared to the hearing range of some animal species. Also, we are most sensitive to sounds around 3,000 Hz. 

Not all mammals' hearing abilities operate in the same range of frequencies. For example, most small mammals are sensitive to very high frequencies but not low frequencies. For instance, some bat species are sensitive to tones as high as 200 kHz, but their lower limit is around 20 kHz.

Do you have a pet? Have you ever noticed how sensitive they are to sudden noises? Similar to wild animals, cats and dogs kept their sensitive hearing to help them avoid danger. In case you wonder if cats and dogs have a more developed hearing than humans, it certainly appears to be the case. The range of sounds they can hear compared to humans is certainly impressive. 

The hearing of cats and dogs ranges from about 20 Hz to 60,000 Hz (60 kHz) - amazingly allowing them to hear even ultrasound entirely inaudible for humans! Other animals, such as dolphins, bats, and elephants hear even higher frequencies - we will touch on these later in the article. Besides high-frequency sounds, dogs and cats can also hear sounds much further away than humans.

Dogs' ears are more sensitive than humans but not as much as cats. However, dogs are excellent at finding sound sources and focusing on them with the help of their highly developed ear muscles. 

A cat's external ear, also known as the pinna, is upright and cone-shaped. It serves a dual purpose - to catch the sound and amplify the sound waves. The cat's ear can amplify sound waves two to three times for frequencies between 2,000 and 6,000 Hertz (Hz). Cats' ears help them hear high-frequency sounds from up to 50 meters away. As a result, some experts believe playing loud music around cats can damage their auditory systems. 

Thanks to the 30 sets of muscles in the cat's external ear, the pinna can move around as much as 180 degrees. A dog's auricle is also very erect and mobile, helping the dog localize the sounds by moving the ears around.

But cats and dogs are only the tips of the iceberg. There are many more members of the animal kingdom with even more impressive auditory systems.

Elephants, with their enormous ears, have impressive auditory abilities. Because of how their ears and ear canals are built, they can pick up infrasound waves much longer than the frequencies humans can hear. In practical terms, this high sensitivity allows them to hear even the movement of clouds and when rain clouds gather. 

Amazingly, elephants can communicate across long distances. By pounding their feet on the ground, they set off powerful but barely audible vibrations that other elephants can pick up miles away with the help of nerve endings in their feet and ear bones. 

Bats have the fascinating ability to get around in the dark like no other animal. Using echolocation, they can find their prey in the darkest hour of the night. How do they do this? They make high-frequency noises, which in turn, bounce off anything in their surroundings and return to the bat's ears. In essence, they use the echoes to build a map of their environment, making darkness completely irrelevant.

Another fascinating feature of bats is that their auditory system appears to extend to the hairs on their wings. As a result, their wings, covered with Merkel hair, are super sensitive to air movements, allowing them to notice objects approaching when they fly and sending this information to their brain for processing. This means that bat hearing is much more evolved than those of humans. They not only hear with their ears but with the hairs on their wings as well. 

So how do they get around? First, they create sonic pulses from their forehead, directing these unique sounds at their target. When the sounds bounce back, the dolphin's jaw receives them, and then the auditory nerves send them to the brain. One of the most significant differences between dolphins' and land animals' hearing is that dolphins' ears - openings on the side of their head - do not seem to play a crucial role in their auditory system.