The sense of hearing develops
early, may be well before birth. The developing baby is surrounded by sound. In
fact, the natural synchrony of the two heartbeats the baby’s is twice that of
the mothers is now thought to constitute our earliest appreciation of rhythm. So,
experiments, showing that babies can be soothed to sleep by recreating sounds
left behind in the womb, have borne this out.
New babies do not learn to
recognize or to locate sound for some months. Like all information received by
the senses, it must first be translated and made sense of by the brain, before
it becomes meaningful. Association is all, whether it is the rattle of a spoon
against a cup, earning food or the soothing words of the mother, meaning
closeness security and pleasure. If a baby is not brought up in a world of
sounds and more specifically words, he or she will fail to associate sound with
meaning and may appear deafer and the age of two or three than the child whose
hearing is actually impaired.
How do we hear?
Sound originates as a movement or
vibration of air, which then sets up smaller vibrations which get fainter and
fainter as they move through the atmosphere. The function of the ear is so
receive and transmit sound to the brain first by amplifying the pressure of the
vibrations as they travel through the ear and second by translating the
vibrations into electrical nerve impulses, intelligible to the brain which then
decodes them. As with sight we hear not with the ears, but with the brain.
Pitch and Loundness
Frequency of sound or pitch is
measured in Hertz. One Hertz is one cycle, or vibration, per second. Middle C
on the piano, for example, is 256 Hertz, or cycles per second. We all respond
to certain frequencies at very subtle level, particularly at the lower end of
the scale, because they set up and generate internal rhythms in the brain. Hence
ht powerful effect of meditative mantras, chanting and rock music.
The human ear starts to pick up
low frequency notes at about 20 Hertz and goes on hearing successively higher
notes to a level of about 20,000 Hertz, after which sounds become too high to
be heard. Some animals, however, can still detect them. Silent dog whistles,
for example are pitched at about 22,000 Hertz, and bats actually navigate by ultrasonic’s,
emitting high pitched squeaks and finding their way by means of the echoes
bouncing off obstacles.
The same principle is used for
radar, depth sounders in submarines, burglar alarms and for medical canning
when X-rays are unsuitable such as during pregnancy. Which sound becomes
perceptible to most people? Some people with an extremely acute sense of hearing
will be able to perceive sound at minus 10 decibels, but this is rare. Hearing
tests work by measuring the quietest perceived sound for different frequencies.
Hearing Tests
One out of every 1,000 children
is born with some degree of hearing impairment. If there is reason to suspect
that the hearing might be damaged, a rudimentary test can be given at birth.
All children should have a hearing test at seven months. Hearing deteriorates appreciable
with age. By the age of 80, one in two people will have a moderate to severe degree
of hearing loss.
This type of hearing loss is very
similar in pattern to noise induced hearing loss. In fact, one study carried
out in the Sudan among a people who live in a world unassailed by urban and
traffic noise and who show a much sharper sense of hearing in old age. It is
suggested that the hearing deterioration we normally attribute to advancing age
might in part at least be noise induced.
If you suspect that your hearing
is not as sharp as it was, have a hearing test. The earlier any impairment is
detected the greater the chance of compensating successfully for it. Using a
hearing aid takes practice and concentration as it does not just amplify
speech, but all foreground and background noise as well.
Noise
Because noise is invisible and
often intermittent it is very difficult to assess both in terms of what the
populations as a whole finds tolerable and of what constitutes a potentially
damaging source of sound. Even so it is now well recognized that exposure to
excessive noise can cause irreversible loss of hearing particularly of the
lower pitched sounds. How loud is too loud? If you have to raise your voice to
carry on a conversation with someone three to five feet away the noise level is
potentially damaging.
Looking After Your Ears?
The less you interfere with your
ears, the healthier they will be. The ear is an efficient self cleansing organ.
The wax inside it picks up dirt and potential irritants as they enter the ear
and prevents them from travelling further down. The warmth generated at body
temperature melts the wax as it accumulates so that both it and the dirt can
run out of the ear quite freely.
The most you should do is to wipe
the outer ear with the corner of a face cloth. Poking around with a finger or
any type of instrument will tend to push the wax further down towards the eardrum
where it is less accessible and more likely to harden and affect your hearing.
If you suspect that an excessive
accumulation of wax is affecting your hearing then to see your doctor who will
arrange to syringe your ears. This is done by directing a jet of water at the
eardrum not at the wax so that the wax is pushed out from the inside. If you
have any history of trouble with your eardrum, you should not have your ears
syringed your doctor will use an alternative method.
Earache is usually referred pain
and often accompanies dental problems. These should be your first ground for
suspicion when or if it strikes. If taking a painkiller every few hours does
not help the problem, do not resort to homespun remedies, go to see your doctor
or dentist.
Having your ears pierced is a perfectly safe
procedure as long as it is carried out under sterile conditions. Stud sleepers
are initially preferable to ring sleepers, as the dirt on your fingers may
cling to the ring ad infect the ears as you turn the ring round. Choose gold in
preference to other metals, as this is the least likely to lead to infection.
If your ears are to flare up consult your doctor. Keep your ears protected from the cold and use
a good sunscreen while sunbathing. So, the cartilage at the top and back of the
ear is particularly susceptible.Source: CP
