Noise Induced Hearing Loss and Its Prevention (cont.)
How effective are hearing protection devices?
Hearing protection devices decrease the intensity of sound that reaches the
eardrum. They come in two forms: earplugs and earmuffs.
Earplugs: Earplugs are small inserts that fit into the outer ear canal. To be
effective they must totally block the ear canal with an airtight seal. They are
available in a variety of shapes and sizes to fit individual ear canals and can
be custom made. For people who have trouble keeping them in their ears, they can
be fitted to a headband.
Earmuffs: Earmuffs fit over the entire outer ear to form an air seal. They
are held in place by an adjustable band. Earmuffs must be snugly sealed so the
entire circumference of the ear canal is blocked.
Properly fitted earplugs or muffs reduce noise by 15 to 30 dB of sound. The
better earplugs and earmuffs are approximately equally effective in sound
reduction. However, earplugs are better protection against low frequency noise
(such as noise from a jackhammer), and earmuffs are better protection against
high frequency noise, (such as noise from an airplane taking off). For high
frequency sounds, think of the high-pitched treble keys of the piano, whereas
for low frequency sounds, think of the low- or deep-pitched bass keys of the
piano.
Simultaneous use of earplugs and muffs usually adds 10
to 15 dB more protection than either used along. Combined use should be
considered when the noise exceeds 105 dB. It is important to understand that
ordinary cotton balls or tissue paper wads stuffed into the ear canals are very poor protectors since
they only reduce noise by approximately 7 dB.
Excessive noise exposure may occur at live rock concerts
as well as in more intimate venues for music whenever amplification is utilized. The damage to
hearing from music is every bit as permanent as that incurred by other means. As
a matter of fact, special high-fidelity earplugs have been developed
specifically for such situations and are being utilized by musicians and
professional sound engineers. These earplugs are specially designed to eliminate
the so-called plugged (occluded) ear effect and to maintain an even reduction of
sound across the frequency range. Otherwise, when the ear is plugged, the
plugged ear effect makes one's voice sound more bass, or deeper, and louder.
Try it by occluding your ear(s) (gently) with your finger, and speak. You'll
hear the plugged ear effect.
Next: What are the common problems with hearing protectors? »
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