Hearing loss is a decrease in the ability to hear. It can vary in degree of loss and occur in one or both ears. There are three parts of the ear. Problems that contribute to hearing loss can occur in one or more of these parts.
Hearing loss is one of the most common health conditions in the United States. Although it affects people of all ages, the numbers increase significantly with age.
Hearing loss is the most common birth defect. Approximately half of the cases of hearing loss in children result from genetic factors. Problems during birth or soon after can also lead to hearing loss, such as lack of oxygen, severe
, or bleeding in the brain.
Two of the most common causes of hearing loss in older adults are
Presbycusis develops slowly as a person ages, especially after age 50, and continues to worsen. It is caused by a combination of hereditary and environmental factors, including exposure to noise and smoking. This condition makes it hard for a person to hear normal conversation and tolerate loud sounds. It sometimes involves permanent damage of the inner ear structures or nerve pathways in the ear leading to the brain
is ringing, hissing, or roaring sounds in the ears. It can occur with any kind of hearing loss and often is caused by loud noise or certain medications. The condition can also be a sign of other health problems, such as allergies and heart and blood vessel conditions. Tinnitus can occur on and off and can stop completely.
Anatomy of the Ear
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There are three main types of hearing loss:
Conductive hearing loss
is due to problems in the outer or middle ear that interfere with sound passing to the inner ear. It usually involves a decrease in sound level and can often be corrected by medical or surgical treatment.
Causes of conductive hearing loss: Blockage by ear waxFluid in the middle ear
Ear infection, also known as
—a disorder of the bones in the middle ear
Hole in the eardrumAbnormalities in the outer ear, middle ear, or ear canalDefect at birth that causes complete closure of the ear canalTumorsTrauma leading to disruption of the bones in the middle ear
Sensorineural hearing loss
is due to damage to the inner ear or the major nerve pathway that goes from the inner ear to the brain. In addition to a decrease in sound level, it also affects the ability to understand speech. This type of hearing loss is permanent. It cannot be corrected medically or surgically, but it can be treated with hearing aids and assistive devices.
Causes of sensorineural hearing loss include: Excess noiseBirth injuryHereditary factorsAging
Exposure to toxic substances, including drugs like:
StreptomycinGentamicinChemotherapy drugsDiureticsSteroidsHeart medicationsQuinineAnestheticsAspirin-containing drugsTumors like acoustic neuromaCardiovascular diseaseMultiple sclerosis
Viruses such as
syphilisNeurologic diseases such as multiple sclerosis and strokeInner ear disorders such as Meniere’s diseaseOtosclerosis affecting the inner earPrevious brain or ear surgery causing damage to the inner earExternal trauma to the ear
Mixed hearing loss
is due to a combination of both conductive and sensorineural hearing loss.