Noise Alert

—ILLUSTRATION: LEIGH HAEGER
Sound waves enter through the outer ear. As they
travel into the auditory canal, the sound waves
vibrate the eardrum. Those vibrations, in turn, move
three tiny bones in the middle ear—the malleus,
incus, and stapes. The bones amplify sound vibrations
so that they can be sensed by the inner ear.
eardrum. When that happens, sound waves
can’t pass to the inner ear. If the damage is
severe enough, permanent deafness can result.
Even if the eardrum isn’t damaged, frequent
exposure to loud noises can still harm hearing.
It can damage sound-sensing cells, called hair
cells, in the inner ear. Each hair cell contains
40 to 100 stiff, hairlike shafts that sense sound
waves. Hair cells transform the sound waves
into nervous system impulses. These impulses
travel to the brain, which uses the signals to
identify the sound.
Damage to the hair cells can prevent them
from picking up sound waves. Continued
exposure to explosive or other loud sounds can
lead to extensive hair cell damage. This can
cause pain, ringing in the ears, and, eventually,
hearing loss, which may be permanent.
Tuned Out
Now, back at the speedway, how do those
guys pump up the volume so loud? And more
to the point, why? I asked Troy Irving.
Irving is a soft-spoken factory supervisor
from Augusta, Mich. He has outfitted his
bright yellow 1985 Dodge Caravan with batteries
that feed 32 amplifiers that send audio
signals to nine speakers. He can’t drive the van
on the road—it’s much too heavy—but, man,
can he make it burp!
An amplifier, or amp, is a device that boosts
the level of an audio signal. Small amps, like
those found in cell phones, might produce
about a half watt of power. (A watt is a measure
of electric power.) Irving’s amps pump
out a total of 130,000 watts!
For Irving, it’s all about maximum volume.
He doesn’t want the money. (There is none.) He
doesn’t want the fame. (There’s none of
that either.) “My goal,” he said, “is to have the
loudest car in the world.”
Say What?
Test your knowledge of hearing loss and its causes.
(See answers in the Teacher’s Guide.)
1. What is one of the earliest symptoms of
hearing loss?
A prolonged ear pain
B a constant ringing noise
C trouble hearing in crowds
D heavy bleeding from the inner ear
2. Which of the following statements is true?
A The use of cotton swabs to clean your
inner ears is harmless.
B By the age of 20, even healthy young
adults can no longer hear some of the
sounds that infants can.
C There is no need to use earplugs when
operating a vacuum cleaner.
D Chronic ear infections can cause only
temporary, not permanent, hearing loss.
3. What is a sign that you may be losing
your hearing?
A Everyone tells you that you mumble.
B You friends and family sound as if they
are stuttering.
C You don’t know if someone has just said
“fish” or “dish.”
D You don’t know if someone has just said
“male” or “mail.”
4. Which of the following situations is most harmful
to your hearing?
A five minutes at a rock concert
B 20 minutes at a dance club
C 30 minutes of listening to music on
your headphones
D two hours in a loud factory
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