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Listen Listen Listen

Listen Listen Listen

To listen means to make an effort to hear something or to pay attention like “Listen to your father”.

A synonym to “listen” is “hear”.

A human hears a sound through his ears.

Human Ear

Human Ear

The ear comprises of three portions: an outer ear (external), a middle ear and inner ear.

Each part performs an important function in the process of hearing.

The outer (external) ear consists of an auricle and the ear canal. These structures gather the sound and direct it towards the eardrum (tympanic membrane).

The middle ear chamber lies between the external and inner ear. This chamber is connected to the back of the throat (pharynx) by the eustachian tube, which serves as a pressure-equalizing valve.

The middle ear consists of an eardrum and three small ear bones (ossicles): malleus (hammer), incus (anvil) and stapes (stirrup). These structures transmit sound vibrations to the inner ear.

In so doing they act as a transformer, converting sound vibrations in the external ear canal into fluid waves in the inner ear.

The inner ear contains the microscopic hearing nerve endings (hair cells) bathed in fluid. Inner ear fluid waves move the delicate nerve endings, which in turn transmit sound energy to the brain by the hearing nerve where it is interpreted into sound.

That is how a human hears a sound.

We humans sometimes have hearing problems. A disturbance of the eustachian tube, eardrum or the ear bones, for example , may result in a conductive hearing impairment.

A disturbance in the inner ear fluids or nerve endings may result in a sensori-neural hearing impairment.

What about the animals ? Do they have hearing problems too?

Certainly any dirturbance  to their hearing systems will impair their sense of hearing too.

But does it matter? No it does not really matter , because their sense of hearing is many times better than ours. And they do not necessarily use their ears to hear.

Let us look at these animals.

Best rain detector – The elephant

Elephants have an exceptional sense of hearing (and smell) and can hear at frequencies twenty times lower than us.

They also use their trunk and feet to hear, both of which are packed with special receptors to pick up on low frequency vibrations.

Elephant

Elephant

And it is believed their low rumble calls can be picked up by other elephants 6 km away.  

One essential reason for such long distance conversation is for females to be able to make as many males in the area aware that she is ready to mate – something that happens only a few days every 2-4 years.

Best navigator using sound – The pigeon

Pigeon

Pigeon

Like elephants, pigeons can hear sounds at exceptionally low frequencies and this helps to explain their exceptional sense of direction.

For example, steep hillsides reflect airbourne sound waves horizontally, providing a unique low-frequency beacon that pigeons can perceive for hundreds of miles.

And there is vast source of such infra-sound in nature – thunderstorms, seismic activity, even the motion of the sea – allowing pigeons to build an acoustic landscape which is totally unknown to us.

Pigeons also possess the equivalent of an in-built compass which allows them to navigate using the Earth’s magnetic field and the position of the Sun. In combination with their hearing – this makes them, probably, the best navigators in nature.

Sharpest hearing – The owl

These birds have phenomenal hearing. Their large ear holes are at slightly different heights, above and below eye level, helping them pinpoint the vertical positions of sound sources.

Owl

Owl

But what is truly astonishing is their reaction time. In complete darkness, it takes tawny owls less than 0.01 of a second to assess the precise direction of a scurrying mouse, for example.

Cats vs. dogs – Cats

Cats win. Not only can they hear higher frequencies than us (and dogs), they can distinguish a sound’s tone and locate its source far better too.

With 30 different muscles, the cat can independently rotate each of its ears 180 degrees, and position one ear or both facing any sound the cat detects.

And thanks to their shape, sound gets funnelled down to a cat’s middle ear extremely effectively.

So effectively, in fact, that from a metre away your average moggy can easily distinguish the sound of you opening the door to the cat food cupboard from the sound of you opening the cupboard door next to it.

Best hearing defence – The tiger moth

So when they hear a bat closing in on them – they can take evasive action, often resulting in a dramatic aerial acrobatic contest between predator and prey; which, more often than not, the bat would win.

Tiger Moth

Tiger Moth

So moths got smarter. Instead of just taking evasive action, they emitted sound back to bat, often emitting as many as 450 clicks in 1/10th of a second.

Such action effectively jams the bat’s sonar and confuses them, allowing the moth to fly another day.

When it comes to hearing, the animals win, hands down.

So in order to make a human hear , sometimes one has to scream and yell.

Sometimes one has to repeat a word many times. Like “Listen listen listen”. Eleven times to be exact.

Watch a video entitled “Listen Listen”

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