Hearing Loss Reading
Eighteen-year-olds are past the age of childhood ear infections that can
adversely affect hearing but are still too young to be suffering the effects of
aging. Assuming that 18-year-olds should have the best hearing around,
researchers in the 1930s and 1950s tested them to set the standard for what
the human ear can hear. By 1969, the summer of Woodstock, audiologist
David Lipscomb found that one-third of the incoming freshmen tested at
the University of Tennessee showed signs of hearing loss. One in eight
male students had damage severe enough to interfere with communication.
(A more recent study for the University of Tennessee's Noise Laboratory
indicated that 60 percent of American college students suffer from some
high-frequency hearing loss.) Researchers immediately suspected that loud
music was the culprit. Live concerts commonly reach sound levels above
120 decibels-louder than a jackhammer or chain saw. According to
standards set by the Occupational Safety and Health Administration,
exposure to sound levels of 85 decibels (comparable to the sound of a food
processor) eight hours a day, five days a week, will eventually cause
permanent hearing loss in most people. For each five decibel increase, the
time it takes to cause lasting injury drops by half. At 120 decibels some
damage can result in a relatively short time.
One ear specialist suggests the following do-it-yourself test for hearing:
Hold your hand up to your shoulder as if you're taking a courtroom oath,
then rub your thumb and forefinger together. If you don't clearly hear a
high-pitched "scritching" sound, you may have some hearing loss in that
ear. Students can find out if they should consider an audiology exam by
taking a simple telephone screening test. (Dial (800) 222-EARS between 9
am and 6 pm Eastern time to reach a national operator who can provide a
number to call for your region; in Pennsylvania, dial (800) 345-EARS and in
Canada, (215) 359-1144.) Although the call to the operator is free in the
United States, the call for the test (which takes 2 minutes) may be long
distance and will be charged at standard rates. It's important that the call
be made from a quiet place since it involves four faint tones delivered to
each ear. The test is not perfect and is best at identifying hearing loss at
middle and low frequencies. Students who fail the test should try again in
a day or two since our ears vary in sensitivity from day to day. Nearby
noise or static on the line may also interfere with the recording.
Some 28 million Americans (350 million people worldwide) suffer some
hearing loss, making this the most common physical disability. In
industrial societies, people gradually lose sensitivity to high frequencies, a
condition called presbycusis. This selective, high-frequency deafness
begins at a very early age. According to one survey, most 30-year-olds are
unable to hear frequencies above 15,000 Hz; by age 50, hearing beyond
12,000 Hz is lost. By 70 years of age, the cutoff value falls to 6,000 Hz, a
value within the range of normal speech. At every age, men exhibit a
greater degree of hearing loss than do women. While some researchers
believe that the cumulative effects of loud noise account for this steady
hearing loss, others believe it is the result of age-related changes in the
cochlea that restrict the blood supply to the delicate neural elements in the
inner ear.
Ringing in the ears, or tinnitus, affects more than 36 million Americans.
Although the most common cause is exposure to loud noises, the disorder
may also be produced by certain drugs, ear infections, or food allergies.
Jack Vernon, director of the Kresge Hearing Research Laboratory at the
University of Oregon, suggests that tinnitus is the third worst thing that
can happen to us, ranking only below intractable severe pain and
intractable severe dizziness. In its severe forms, tinnitus is totally
incapacitating, making it impossible for people to concentrate enough to
complete a task. Some people gain relief by using a tinnitus masker; worn
like a hearing aid, it produces a sound like a waterfall or the hiss of an FM
radio tuned between stations.
Jaret, P. (1990, July/August). The rock and roll syndrome. In Health, pp. 51-57.
Matlin,
M., &Foley, H. (1997) Sensation and perception (4th ed.). Boston: Allyn and
Bacon.
Sekuler, R., & Blake, R. (1994). Perception (3rd ed.). New York: McGraw-Hill.