Conductive Hearing Loss
A conductive hearing loss is caused by a problem in the outer or middle ear. A conductive hearing loss reduces the loudness (intensity) of sound reaching the inner ear (Cochlea). Such a loss can occur when the outer ear canal is blocked with wax or a foreign object. Problems occurring in the middle ear space include: middle ear infections; dislocation of middle ear bones; boney growth or stiffening; holes in the eardrum; hardening of the eardrum. The main result is a drop in the loudness of sounds. A conductive loss can often be partially or completely corrected by medication or surgery. Following the completion of medical treatment for causes of the conductive hearing loss, hearing aids are often effective in assisting any remaining hearing loss.
Sensorineural Hearing Loss
Sensorineural hearing loss is due to damage to the inner ear (Cochlea) or the auditory nerve which carries the message to the brain. Like conductive hearing loss, sensorineural hearing loss reduces the intensity of sound, but it might also introduce an element of distortion into what is heard resulting in sounds being unclear. A person with a sensorineural hearing loss may lose the ability to hear speech clearly even when it is very loud. Some causes of sensorineural hearing loss include: meningitis, head injuries, drugs, hereditary causes, the aging process itself as well as exposure to very intense noise. Sensorineural hearing loss cannot be medically treated at this time. An individual may benefit from a hearing aid, communication therapies or other medical management.
Mixed Hearing Loss
In a mixed hearing loss, both a conductive and sensorineural component are present. In addition to some irreversible hearing loss caused by an inner ear or auditory nerve disorder, there is also a problem with the outer ear or the middle ear mechanism that makes the hearing worse than the sensorineural loss alone.
The conductive component may be treatable and this component of the hearing loss may be completely or partially corrected, but the sensorineural component will most likely be permanent. Hearing aids can be beneficial for individuals with a mixed hearing loss. An example of this could be wax blocking the ear canal and a sensorineural hearing loss due to aging. Once the wax is removed, the remaining sensorineural hearing loss can be assisted with hearing aids.
Central Hearing Loss
Central hearing loss is caused by a problem with the auditory nerve or sound centres. Sound waves may travel through the ear but this nerve pathway is unable to send electrical impulses to the brain. As a result the hearing centres do not receive the signals correctly. Central hearing loss can be a result of a head injury or disease. A common symptom is the ability to detect sound but not being able to understand it.