Causes

Presbycusis: age-related hearing loss

Presbycusis is the loss of hearing that gradually occurs in most people as they grow older. It typically begins in the 40s and gradually grows worse. Normal wear and tear that comes with age damages the inner ear, most commonly. But loss of hearing can also result from changes in the middle ear or from complex changes along the nerve pathways leading to the brain. This process interrupts the transfer of sound waves to the inner ear and auditory nerve.

More common in men than women, presbycusis first affects a person's ability to hear high-frequency sounds. If you start noticing that it is increasingly difficult to differentiate certain sounds such as "th" and "sh" or understand women and children, who tend to have higher pitched voices, you may be exhibiting the first signs of presbycusis. Having trouble hearing conversations on the telephone is also common. Researchers have determined the condition has a genetic or hereditary component. If one or both of your parents suffer from it, chances are higher that you will, too.

The long-term effects of repeated exposure to loud noises, such as traffic sounds or construction work, noisy machinery, and loud music, can cause presbycusis.

Presbycusis may also be caused by changes in the blood supply to the ear because of heart disease, high blood pressure, and other conditions caused by diabetes or other circulatory problems.

Sometimes presbycusis is a conductive hearing disorder, meaning the loss of hearing is caused by problems of the outer ear and/or middle ear. This may be the result of damage to the eardrum or the three tiny bones in the middle ear that carry sound waves from the tympanic membrane to the inner ear.

Other causes of hearing loss

Otitis media, or middle ear infection, is the most common infectious cause of temporary hearing loss in the United States.

Meningitis, chronic middle ear infections, measles and other illness can cause hearing loss, as well as injuries to the face or head and certain drugs (such as the antibiotic gentamicin and aspirin). Hearing loss can also occur as a result of hereditary factors and various health conditions.

Hearing loss in infants

The following are causes of sensorineural hearing problems in infants:

• Infection while still in the womb, such as rubella.
• Low birth weight.
• High bilirubin count (jaundice).
• Problems during delivery.
• Some medications harmful to the ear taken during pregnancy, such as aminoglycosides (a class of antibiotics), certain water pills, and certain chemotherapy drugs.

More on Hearing Loss

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This article was reviewed and updated June 2007.