Kinds and Causes
Hearing loss is the most common sensory defect in humans. There are about 28 million people who suffer from hearing loss in the US alone. Almost 15% of American children suffer from either low- or high-frequency hearing loss.
Some causes of hearing loss/deafness:
In those 65 years of age or more, 10% have enough hearing loss to affect communication.
Conductive hearing loss, or conductive deafness usually caused by disease of injury to the eardrum or the bones of the middle ear, which prevent sound waves from being conducted to the cochlea.
Almost all conductive hearing loss can be repaired medically or surgically.
In rare cases, a person can be fitted with a hearing aid that bypass the middle ear, using bone conduction to send sound vibrations to the cochlea.
Sensorineural hearing loss
This is the most common type of hearing loss in adults. Involves damage to either the cochlea or the auditory nerve. Large numbers of the cochlea's delicate hair cells, which transduce sound waves into neural impulses, may be damaged or destroyed. If the damage is not too severe, a hearing aid may help. If the damage is to the auditory nerve, hearing aids are useless.
Although hearing loss occurs most often in older people, 75% of cases are apparently from lifelong exposure to noise rather than ageing.
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