Broadly speaking, hearing loss is classified as Conductive hearing loss, Sensorineural
hearing loss or Mixed hearing loss.
Conductive Loss
Conductive hearing loss is caused by the obstruction of sound being transferred to the
inner ear. This could be due to wax (cerumen) blocking the pathway of sound or problems
in the middle ear such as middle ear infections or tympanic membrane perforations
(hole in the ear drum). Most conductive hearing losses can be reversed or corrected
by medical intervention.
Senorineural Loss
This form of hearing loss is caused by damage to the hair cells in the cochlea (inner
ear). Damaged hair cells send out weaker electro-chemical signals to the brain, which
in turn gets less information. The majority of hearing losses fall into this category.
This type of hearing loss is non-reversible.
Mixed Loss
This type of hearing loss is a combination of conductive and sensorineural hearing
loss. The severity of the hearing loss depends on the involvement of the conductive
and sensorineural components of the hearing mechanism.
Neural loss
This type of hearing loss is due to problems in the auditory neural pathway
(ie. The auditory nerve) which conducts sound to the brain.
All types of hearing loss can be treated with hearing aids, auditory implants, cochlear
implants or brain stem implants depending on the nature and the degree of hearing
loss.
Age
Age is one of the major contributors to hearing loss. As we grow older our bodies start
degenerating along with the hair cells in the inner ear (cochlea). As hearing is
a psycho-physiological phenomenon it also depends on how alert we are to receive,
process and decipher sounds.
Noise
Noise is one of the major causes of hearing loss. Overexposure to noise can be
due to workplace noise exposure or recreational noises such as loud music and personal
music players (iPods) or other loud noises such as gunfire.
Drugs
Certain chemicals and drugs can damage your hearing if taken over long periods of
time. This mainly affects the inner ear.
Disease
Some diseases, such as measles, mumps, rubella (German measles) and meningitis,
can cause loss of hearing.
Infections
Outer ear, middle ear or inner ear infections can cause hearing loss. This can be
treated medically and can be reversed if intervention is early enough to prevent
permanent damage.
Injury
Injuries, including perforation of the ear drum, fractured skull or large changes
in air pressure (barotrauma) can also cause hearing loss.
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