What is Deafness?
A hearing loss occurs when the brain does not receive enough sound information from the ears. The ear is divided into three parts: the outer ear including the visible part of the ear and the ear canal; the middle ear consisting of the ear drum and the three bones attached to it; and the inner ear which is the sense organ that creates nerve impulses which travel up the hearing nerve to the brain. A problem with any of these parts of the ear can lead to a hearing loss.
Hearing losses can be temporary, permanent or fluctuating and they can affect one or both ears. They are divided into two types: conductive hearing loss and sensorineural hearing loss.
Conductive Hearing Loss
A conductive hearing loss is caused by a mechanical problem with the way sound travels into the ear. It may be a blockage such as wax and foreign objects, or a physiological problem such as fluid in the middle ear (glue-ear). Sometimes a conductive loss can be corrected with surgery or other interventions and the hearing is restored.
As the inner ear is unaffected by a conductive loss, if a loud enough sound can be put in the ear via a hearing aid then near-normal hearing can often be restored successfully.
Sensorineural Hearing Loss
A sensorineural hearing loss is caused by damage to the inner ear or to the hearing nerve which carries information from the ear to the brain. Unlike some other nerves, neither the inner ear nor hearing nerve is very good at healing themselves. Therefore, a sensorineural loss tends to be permanent, although the amount of loss can fluctuate.
As a sensorineural loss is caused by permanent damage to the inner ear or nerve, normal hearing can never be fully restored with a hearing aid. However, good benefit can be achieved with hearing aids and even profound hearing losses can be helped.
Where there is very little hearing left, a cochlear implant may be used instead of a conventional hearing aid. Cochlear implants are special hearing aids which are surgically implanted into the inner ear and which stimulate the nerve of hearing artificially.