Judy
Oskam and Julie Mitchell
Oklahoma Cooperative Extension Service
Hearing
loss is not just a consequence of old age. Noise induced hearing
loss ranks among the top 10 work-related conditions outlined
by the National Institute for Occupational Safety and Health
(NIOSH). Agricultural workers experience one of the highest
rates of hearing loss caused by loud noises on the farm. Studies
have shown that farmers and other agricultural workers may
experience substantial hearing loss by the age of 30.
Prolonged
exposure to agricultural noises could result in permanent
hearing loss unless noise control measures are taken.
COMPONENTS OF THE
HUMAN EAR: THE EXTERNAL EAR, MIDDLE EAR, AND INNER EAR
Table
1. Decibel levels of everyday sounds. |
Decibel
Level |
Common
Sounds |
0 |
Faintest
sounds heard by ear. |
30 |
Whisper,
quiet library. |
60 |
Normal
conversation, typewriter. |
90 |
Lawn
mower, shop tools, truck traffic; eight hours per
day maximum exposure. |
100 |
Chain
saw, pneumatic drill, snowmobile; two hours per
day maximum exposure without protection. |
115 |
Sandblasting,
loud rock concert, auto horn; 15 minutes per day
maximum exposure without protection. |
140 |
Gun
muzzle blast, jet engine; noise causes pain and
brief exposure injures unprotected ears. |
Hearing
Protection is a Must |
|
Table
2. Recommended exposure time for sound levels |
Sound
Level |
Max.
Duration (Hours per Day) |
90 |
8 |
95 |
4 |
100 |
2 |
110 |
1/2(30
minutes) |
115 |
1/4(15
minutes or less) |
Limit
your exposure to noise levels louder than 90 decibels
to specified duration over an eight hour period. |
|
The middle
ear is made up of three tiny bones or ossicles that transmit
noise vibration to the inner ear. Noise will not affect the
middle ear unless the sound impact or pressure is so great as
to cause the bones to dislodge or fracture.
The
inner ear is highly susceptible to damage from overall exposure
to loud noise. It is composed of hair-like structures that
transmit noise messages to the brain by changing mechanical
energy to electrical energy. With repeated noise exposure,
hair cells are destroyed, causing substantial hearing loss.
Sound is energy transmitted through the air. It has two qualities--loudness
and tone.
Sound
is measured in units of decibels, ranging from the softest
sounds heard by humans to the most detrimental sounds that
will cause hearing loss (See Table 1). There are recommended
exposure levels that everyone should follow (See Table 2).
Noise is potentially too loud when you have to raise your voice
in order to communicate over the sound or you experience one
of the following warning signs:
- Your
ears ring after prolonged exposure to noise.
- Speech
and other sounds seem muffled after exposure.
- You
lose the ability to tell musical tones apart.
- You
fail to hear high pitched sound.
- You
feel a fullness in your ears.
According
to a 1981 EPA estimate, 10 percent of the 3.6 million United
States farm workers are exposed to average daily noise levels
in excess of the 85 decibels. An unknown portion of the additional
11.8 million farm family members, part-time farmers, and hired
workers may also be exposed to potentially hazardous noise.
Noise exposure has several effects that can alter your everyday
routine.
- Psychological
effects--Over a long period of time, noise can cause fatigue,
irritability, and communication problems.
- Physical
problems--Noise can cause constriction of small arteries
in the fingers, toes, skin, and abdominal organs. The heart
pumps less blood with every beat in noisy environments.
It can weaken our natural resistance to disease, affect
our nervous system, and cause headaches.
Hearing
loss can be prevented. There are a variety of ways to reduce
agricultural noise.
Engineering
Controls
- Replace
worn, loose, or unbalanced machine parts.
- Make
sure that machine parts are well lubricated.
- Install
a good, high-quality muffler to all engine-powered equipment.
- Isolate
yourself from noise sources with an acoustic tractor cab.
Work
Schedules
Arrange
work schedules so that workers don't exceed the noise exposure
limit.
Ear
Protection
If you are
continually working in hazardous noise areas, you should wear
some sort of hearing protection.
There
are two types of protectors that work effectively if worn
properly.
- Ear
muffs--This type of protection is the most effective. The
noise reduction will vary greatly, depending on the size,
shape, seal material, shell mass, and type of suspension.
- Ear
plugs--Plugs are another form of ear protection. They are
usually made from rubber, plastic, or foam. When buying
ear plugs, follow the directions so that a snug, tight fit
is obtained in the ear canal when the plug is inserted.
Ear
plugs and ear muffs do not affect your ability to communicate
with others. People around you cannot give verbal warning
over the loud noise anyway. Ear plugs do not alter or interfere
with a co-worker "getting your attention."
Never
use cotton for the purpose of reducing noise exposure; it
does not block out high frequency sounds and does not provide
protection!
Agricultural
work is one of the most dangerous occupations in the United
States. Whenever possible, safety precautions should be taken.
Though
many people are unaware of it, over exposure to loud noises
can gradually damage your hearing. Noise induced hearing loss
is not like other types of hearing loss--it can be reduced
or prevented. Once the damage has occurred, no treatment
can correct your hearing.
Note:
If you suspect you have some sort of hearing loss, contact
your physician or local health department for more information.
If you are continually exposed to noise, take all appropriate
precautions.
- American
Academy of Otolaryngology
- Dr.
Donald Crawley, Oklahoma Ear Specialist
- Farm
Safety Association
- OSHA
Noise Standard
- National
Institute for Occupational Safety and Health
- The
University of Missouri-Columbia Cooperative Extension Service
- The
Pennsylvania State University Cooperative Extension Service
Disclaimer
and Reproduction Information: Information in NASD does not
represent NIOSH policy. Information included in NASD appears
by permission of the author and/or copyright holder. More
NASD Review: 04/2002
For
more information about agricultural safety and health, contact:
Project Director, Oklahoma Agricultural Health Promotion System,
Department of Biosystems and Agricultural Engineering, 226
Agricultural Hall, Oklahoma State University, Stillwater,
OK 74078, Phone: 405-744-5427; or The National Institute for
Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati,
Ohio 45226, Phone: 800-35-NIOSH (800-356-4674)
Assistant
Extension Specialist, Biosystems and Agricultural Engineering,
Oklahoma University; Project Assistant, Biosystems and Agricultural
Engineering, Oklahoma University.
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