What picture springs to mind when you think about hearing loss? A puzzled-looking older person struggling to participate in a conversation? Two college students signing animatedly to each other? A construction worker with his hand cupped around his ear trying to hear above the din at the site? The fact is all of these are pictures of hearing loss.
Who is affected by hearing loss?
Hearing loss is the most common physical disability in the United States. In the United States alone, about 28 million people have some level of hearing impairment that interferes with their ability to understand normal speech and participate in conversations. Another 2 million are cannot hear at all.
Age is the most common risk factor in developing hearing loss. About 30 percent of people between 65 and 74 experience some difficulty in hearing. That percentage and severity of the loss increases with age.
Hearing loss not only affects the elderly. Among people 45 to 65 years of age, about 14 percent have some hearing impairment and another 8 million people between 18 and 44 do as well. A nationwide study estimated 7 million children have some hearing loss, although some experts believe that estimate is too high.
What are the major types of hearing loss?
There are two major types of hearing loss and both can occur in the same person. To understand them, it helps to understand how the ear works. Your outer ear gathers sound waves from the environment and funnels them into the ear canal. At the end of the canal, the waves strike the eardrum, causing it to vibrate. Three tiny bones in the middle ear conduct the vibrations from the eardrum to the cochlea a spiral-shaped chamber that looks somewhat like a snail) in the inner ear. If anything interferes with the transfer of sound waves up to this point, the resulting type of hearing loss is called conductive.
Problems beyond this point lead to sensorineural hearing loss, also known as nerve deafness. Normally, the vibrations from the middle ear create waves in the fluid inside the cochlea. The waves in turn stimulate thousands of delicate hair cells that line the cochlea. Their movement generates nerve impulses in the auditory nerve, which lies just beyond the cochlea and carries the impulses to the brain. Ultimately the brain interprets and makes sense of sound, distinguishing and giving meaning to words, music and everything else you hear. Anything that damages the hair cells or blocks the transmission of the nerve impulses can lead to sensorineural hearing loss.
Conductive hearing loss may be temporary or permanent. It can be caused by something as simple as a buildup of earwax or an ear infection. Sensorineural hearing loss, which is almost always permanent, is most often caused by presbycusa, a form of age-related hearing loss that destroys hair cells.
Surgical procedures and medications can frequently treat conductive hearing loss, but only rarely can they help people with sensorineural hearing loss. Even so, nearly all people with hearing problems can be helped by hearing aids.
