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Sunday, 28 February 2010

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Human ear and sound dimension

What is more precious: vision or hearing? Most of you will say that vision is more precious because you treasure your eyes more than your ears. However, there is increasing evidence to show that hearing is more important than vision. A baby for instance, first responds to sound than to sight. Even the human foetus listens to its mother's heartbeat. This is why most lullabies repeat the sound of the heartbeat.

The human ear is a complex but marvellous creation. The eardrum vibrates in response to various sounds we hear. The outer ear acts as a reverse megaphone designed to collect and bring sounds into the inner ear. The two outer ears on either side of the head helps with sound localisation. If not for them we may not be able to identify the direction from which a sound is emanating.

Sounds are wave patterns in the air that enter each ear at slightly different times and the brain uses the time difference to ascertain the origin. The outer ears also help us to delay or amplify sounds of particular frequencies. When the sound waves hit the eardrum, it vibrates. These vibrations are picked by the middle ear which contains three bones.

Despite all these complex organs, our auditory range is very limited. For instance, we hear only sounds lower than 20 vibrations per second. If we could hear all the sounds in our surroundings we are unlikely to keep our sanity. Even within our limited range we hear only some selected sounds. Our ears block out many sounds we do not like to hear.

Whether you like it or not we hear many sounds and voices. Hearing them we become aware of our presence in this mighty world. Wherever there is air we hear some sounds. As our environment is full of air we cannot do without sounds. Even if we do not talk or make any other noise, we may hear the sound of speeding traffic, and the swaying of trees. If there is absolute silence in our homes and workplaces, we will feel depressed. We must remember that every event taking place has a sound dimension.

Erasmus Darwin

By nature our ears are sensitive to sound. There is an interesting story about Erasmus Darwin who was the grandfather of Charles Darwin. One day Erasmus Darwin had an unusual visitor. He was Justice Fielding, a blind man. Fielding walked into Darwin's room for the first time and exchanged pleasantries. After some time he said, "This room is about 22 feet long, 18 feet wide and 12 feet in height." Fielding had guessed the exact size of the room by ear!

Blind people make use of their hearing capacity to the maximum. Even when they carry a white cane or similar object they tap them on the ground to make a sound. They interpret the echo effectively and move on without knocking against other people or objects.

One remarkable quality of the human ear is that it can pick out a specific sound or voice from a welter of sounds. For instance, a mother can locate her crying child even if he happens to be in a crowded hall. Although she cannot see the child her ears will help her to find the missing child.

This amazing ability of the mother is due to the fact that she has two ears. A sound to the left of us will reach the left ear first. The same sound will reach the right ear after a fraction of a second. This time lag helps us to locate people.

It is quite natural for us to hear various sounds and voices when we are awake. When we are fast asleep we usually do not hear any sounds or voices. However, a mother who is fast asleep may hear her baby crying. Similarly, if somebody calls you by name while you are fast asleep, you are likely to wake up! This fact also shows that our ears are marvellous creations!

We hear different sounds at different times. In a busy office you hear the ringing of telephones, the sound of moving traffic and constant chattering among workers. When you go home, you hear the sound of television, the radio or the CD player. You will also hear your mother or wife chopping vegetables in the kitchen or children making various noises.

You can improve your hearing if you care to do some simple exercises. For instance, close your eyes and listen to the footsteps of the people who enter an office. After some time you will be able to tell exactly how many people entered the office. However, you cannot do this exercise with a crowd or mob.

By the way, what is the sweetest sound you like to hear? The answer is simple. That is your own voice! Great speakers and singers talk and sing mainly because they love to hear their own voices.

The delicacy of the organs involved in hearing makes the ear vulnerable to damage. Exposure to intense levels of sound can eventually result in hearing loss. For instance, in the United States alone there are about 28 million people who have some degree of hearing impairments. Meanwhile, medical opinion is divided whether we should restore hearing to a deaf person. According to some experts, deafness represents a legitimate culture. Others, however, oppose this opinion.

 

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