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Types
of Hearing Loss |
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Conductive Hearing
Loss |
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- Occurs when sound is not
conducted efficiently through the outer and middle ears,
including the ear canal, eardrum, and the tiny bones, or
ossicles, of the middle ear.
- Usually involves a reduction in
sound level, or the ability to hear faint sounds.
- Usually mild or moderate hearing
loss
- Can be temporary in some cases
- Can usually be medically or
surgically corrected
- Can be caused by obstruction of
the ear canal, infections or fluid in the middle ear space,
perforations of the ear drum, and the abnormalities of the
middle ear hearing bones.
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Sensorineural
Hearing Loss |
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- Occurs when there is damage to
the inner ear (cochlea) or to the nerve pathways from the
inner ear to the
brain
- Involves a
reduction in sound level, or ability to hear faint sounds and affects
the ability to understand speech or hear clearly
- Can be caused by diseases, birth
injury, drugs that are toxic to the auditory system, and
genetic syndromes
- May also occur as a result of
noise exposure, viruses, head trauma, aging, and tumors
- May be mild, moderate, severe,
profound or total hearing loss
- Cannot be corrected medically or
surgically. It is a permanent loss
- Treatment includes hearing aids
or a cochlear implant
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Auditory
Neuropathy |
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Auditory neuropathy is not a type of
hearing loss but a dysfunction in the hearing system in which the
auditory nerves do not respond to sound in a coordinated fashion.
Symptoms seen in auditory
neuropathy include the following:
- Hearing
test suggests a mild to moderate hearing loss
- Absent
acoustic reflexes
- Absent
or severely abnormal auditory brainstem responses
- Word
recognition ability poorer than expected for the amount of
pure tone hearing loss
- However,
a major distinguishing feature is that in these patients
otoacoustic emissions are present suggesting near normal
cochlea function.
In auditory neuropathy the cochlea
hair cells are responding to sound, but the auditory nerve does
not transmit the signals to the brain in a coordinated, useful
fashion. Since the cochlea is working in these patients a hearing
aid is not appropriate since the ear does not need more volume of
sound. In severe cases of auditory neuropathy a cochlear implant
can be effective in synchronizing the auditory signal.
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