Hearing Aid – Noise pollution

Hearing Aid

Patients with a conductive defect which does not respond fully to
treatment may be helped with a hearing aid.
A hearing aid is an electronic, battery-operated device that
amplifies and changes sound to allow for improved communication. Hearing
aids receive sound through a tiny microphone, which then
converts the sound waves to electrical signals. The amplifier increases the
loudness of the signals and then sends the sound to the ear through a speaker
in an ear piece which fits into an outer ear canal. The electric signals are
converted back to sound waves.

A volume control on the aid usually operated by turning a tiny wheel
enables the level of incoming sound to be adjusted.
More powerful aids that amplify sound to a greater
degree are available. In these aids the microphone, amplifier and
battery are contained in a larger case worn on the body; the currents is
carried to the ear piece by a thin wire. Some people with conductive
deafness especially if there is an infection or discharge in the ear canal may
be given a bone condution hearing aid. This type of hearing aid may be fitted
to a glass frame or hair band.

Other devices available for the hard-of-hearing include
amplified telephone receivers, flashing lights instead of door bells and
telephone bells, vibrators that respond to sound, head phone for
television sets, teletype writers and guide dogs for the deaf.

Noise pollution

The term noise is derived from the Latin word Nausea refering to the
feeling of sickness in the stomach with an urge to vomit. Any unpleasant and
unwanted sound is considered as noise. It is one form of pollution. Noise
pollution can be defined as unwanted or offensive sounds that unreasonably
intrude into our daily activities. It is responsible for various adverse effects.
In recent years noise is recognized as a major pollutant on par with other
chemical pollutants of air, water and biosphere. Noise has many harmful
effects on man and the damage incurred is irreversible.

There are various sources of noises and the sources are broadly
classified into industrial sources and non industrial sources. The noise dumped
into the atmosphere by the industires due to the functioning of machineries
form the industrial sources. On the other hand the noise associated with
urban development; road, air and rail transport; loud speakers, radio and
television stations, construction sites, neighbourhood and recreational noise
levels, and activities associated with urban living generally lead to increased
noise levels.

Sound is measured by several complex systems. The best known
unit of measurement is the measurement of sound in decibel which is named
after Sir Alfred Bell. The industrial noise survey of India recognized noise
levels from 81dB to 120dB as permissible levels.

Loud noises (above 130 dB) can cause immediate and permanent
damage to the muscles in the middle ear, altering the stiffness of the ossicles,
damaging the hair cells of the cochlea and casuing the rupture of ear drum
thereby reducing the efficiency of hearing.

Prolonged exposure to unpleasant noises may lead to severe mental
distubances and violent behaviour. Noise is also partially responsible for the
increased consumption of alcohol, drugs, tranquillzers and sleeping pills. Noise
pollution further contributes to a few cardiovascular problems. Peptic ulcers
and asthma are aggravated. Small vessels to glomerular circulation are
subjected to vaso constriction and ultimately the output of urine is reduced.

Persons exposed to excessive noise at work place have temporary
impairment of hearing.

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