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Understanding the gauge -

One hertz is equal to one cycle per second. The number of pressure variations per second is called the frequency of sound. So 64 hertz, for example, means 64 vibrations per second. 

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Low frequency and high frequency -

This would translate to us as a very low frequency. Generally, the more vibrations per second, the higher the tone.

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Dogs -

Dogs can hear sounds up to 45,000 Hz. They can perceive much higher tones than humans. Dog whistles emit a high pitch tone that dogs can’t ignore, and we can’t hear.

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Human hearing -

Human beings can hear approximately between 64-23,000 Hz.

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Evolution -

Generally, we can presume that the majority of nature hasn’t happened by accident, and, most often, animals will have a specific trait because they have developed it to survive.

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A basic example -

For example, rabbits are fast because slow rabbits got caught by predators and eaten and therefore weren’t able to pass on their slow rabbit genes.

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Birds use their sense of sound to avoid prey -

Many birds will fly away when we approach them. But it is their keen sense of hearing that allows them to detect our approach, not their sight.

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The asymmetrical ears of owls -

Owls have one ear slightly ahead of the other, allowing them to be more precise in their hearing, aiding them in pinpointing their prey's distance and position.

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Moths -

The moth is prey to most animals and insects with its lack of defensive mechanisms. But the moth has survived into the 21st century because of its hearing. Scientists say that some moths can hear 150 times more than any human.

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Ears at the back of their heads -

Many feline species have more than three dozen muscles sounding their ears, allowing them to rotate their ears 180 degrees. In comparison, humans use three muscles and three of the smallest bones in our body for hearing.

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Infrasound -

Elephants, because of their ears and ear canals' architecture, pick up what is called infrasound waves. 

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How elephants benefit from hearing infrasound -

This ability enables them to hear when rain clouds are gathering, meaning they can go to viable water sources to drink water when it rains.

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Pigeons hear infrasound too -

Infrasound is too low for humans to hear, but pigeons can hear it also. Pigeons can tell when rain and storms are coming so they can stay out of their way.

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Whales and dolphins -

Dolphins can hear sounds underwater from as far as 15 miles (24 km) away, and whales' voices can travel 479 miles (770 km) through the waters of the ocean.

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A common example -

Sound is as important for some species in nature as sight, and some species rely on it entirely. The bat is the most famous example.

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Can animals interpret music? -

It’s complicated for scientists to understand how music affects animal’s brains. This makes sense considering music is not static and often includes several sounds happening at once instead of a single uniform tone.

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Dogs enjoy classical music -

Furthermore, research led by Deborah Wells, a psychologist at Queen's University Belfast, proved that dogs could discern between human music of different genres.

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Metal is stressful -

Dogs can show agitation when exposed to certain types of music, such as heavy metal, and feel relaxed when exposed to classical music.

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Cows and music -

Did you know that cows that listen to music end up producing more milk than those that do not?

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Music is a distraction -

It’s speculated to be less about the music and more about the music being a distraction from the loud and unsettling sounds in dairy farms that cause stress for the cows, making them produce less milk.

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Animals can't understand key changes -

Cats, dogs, and some primates can also learn to recognize specific sequences of notes. However, if the series of notes are transposed to another key, they won’t recognize the relationship between the notes.

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In contrast -

Humans, on the other hand, do this automatically. Humans can recognize sequences of notes no matter what key they’re in.

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Animals compete for frequency spectrums too -

Sound mostly plays the role of survival. As animals compete for resources like food, water, and space to live, they have been competing too for frequencies to communicate through.

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Birds adapt their calls to their environment -

As we now know, animals can have an advantage for survival by hearing more. David Attenborough and many others have claimed that bird sounds have evolved to fit their environment.

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Bird calls -

For example, in dense foliage, a constant repetitive sound works best. If the recipient doesn’t receive the first sound signal, another one will soon follow.

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Ground-dwelling birds -

Birds that live on the ground have adapted to lower-toned calls, as higher-toned calls would bounce more and become more easily distorted.

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Birds buzz near water -

Birds that live near water and in vast lands, like the Savannah sparrow, have developed buzzing calls that can travel long distances.

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San Francisco's birds are adapting to loud traffic -

The evolution of sound in nature hasn’t stopped. Birds in San Francisco have been found to raise the tone of their calls over the past 40 years to be heard above noises of increased traffic.

Sources: (Healthy Hearing) (Louisiana State University) (How Music Works)

See also: The world's strangest natural wonders

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