Dennis Zeimet, Charles
V. Schwab and Laura
Miller
Iowa State University Extension
Table
1. Common noise levels (in decibels) |
Jet
airplane |
140* |
Pig
squeals |
130* |
Chain
saw |
115 |
Loud
rock music |
115 |
Chickens
(inside building) |
105 |
Table
saw |
100 |
Shop
vacuum |
98 |
Garden
tractor |
92 |
Tractor
wearing HPDs |
85-95 |
Lawnmower |
85 |
Electric
drill |
88 |
Quiet
whisper |
20 |
Note:
Each increase of 6 decibels doubles the noise level
* Above 130 decibels causes pain. |
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The traditional
picture of a farm as a serene and quiet workplace couldn't be
farther from the truth. Machinery, even sounds made by animals,
create a sometimes noisy and often hazardous environment.
The
noisy farm environment has taken its toll on many farm operators'
hearing capabilities. A central Iowa farm health clinic found
that 70 percent of farmers given a routine hearing test had
below normal hearing for their age. At least 30 percent suffered
hearing loss significant enough to warrant an assistive hearing
device.
Table
1 is a chart of sounds commonly heard by people involved in
agricultural activities. Continuous sounds of 85 decibels
or higher are considered hazardous. Any time you have to shout
to be heard by someone standing 3 feet away, the noise level
is probably greater than 85 decibels. Every 6-decibel increase
doubles the sound. For example, a table saw (100 decibels)
is twice as loud as a garden tractor (92 decibels).
Distance
from the noise source also is important. As a person moves
away from the sound, loudness drops off quickly. For example,
someone 9 feet rather than 3 feet away from a chain saw will
hear 103 decibels and not 115 decibels. The key is to keep
noisy equipment as far away as possible. When that's not possible,
wear hearing protection devices (HPDs) to get noise within
the acceptable 85-decibel range.
Some
hearing loss occurs naturally as part of aging. Generally this
does not become severe unless people are continually exposed
to noise. Therefore, it is important to avoid excessively loud
noises to prevent additional hearing loss that could lead to
a disability.
Hearing
loss will occur even if people say they have become "used
to the noise" or ignore it. Many people say they can "block
out" noise, but damage will continue unless the hazardous
noise level is reduced.
Although
noisy environments can lead to permanent hearing loss, they
also can affect people in other ways. Noisy environments can
lead to increased anxiety, hypertension, and fatigue. Many
people who wear hearing protection comment that they feel
better in general at the end of the day.
Most
people cannot detect their own hearing loss because auditory
damage occurs slowly over time. Usually, a person with a hearing
loss may think other people are mumbling and need to "speak
up" or enunciate better. If in doubt, get a hearing test by
an audiologist, available at most hospitals and clinics.
Hearing
loss can be prevented with the proper use of hearing protection
devices (HPDs). These devices provide a barrier between the
sound and the ear, or absorb sound waves before they enter the
ear. Persons with normal hearing always can detect some sound
while wearing HPDs because bones in the head conduct sound.
You
may want to consider HPDs if:
- you
work in noisy conditions that have a continuous decibel
level greater than 85;
- you
experience "ringing" in the ears after being in a noisy
area;
- you
are bothered, nervous, or anxious after being in a noisy
area;
- you
want to increase your comfort;
- you
are unusually fatigued after working in a noisy area, or
- your
doctor recommends one.
Not
all HPDs provide the same level of protection. Consider the
following aspects:
Style.
The most common hearing protection devices are muffs worn
over the ears, and plugs worn in the ears. Muffs may be more
comfortable to wear for long periods of time than plugs. Muffs
should not be worn with eyeglasses or any other obstruction
that will reduce their effectiveness.
Hearing
plugs may be disposable or designed for re-use. Disposable
plugs are especially popular for short wearing periods or
infrequent use. They are inexpensive and can be thrown away
when the job is completed or they become dirty. However, disposable
plugs can be relatively expensive if hearing protection is
required on a regular basis. In this case, a non-disposable
plug or muff, meant to be washed and stored after each use,
is a good choice.
Effectiveness:
Not all materials can block the same amount of sound. An HPD
manufacturer must indicate how much noise (in decibels) the
device will reduce for the wearer. This is listed on the package
as the noise reduction rating (NRR). For general use, look
for NRR of 25 or greater. Remember that the rating was obtained
in perfect conditions after wearers had received careful fitting
instructions. A more realistic estimate is about half the
manufacturer's NRR. For example, expect a d vice with a 30
NRR to reduce noise by about 15 decibels. This means that
a 95-decibel noise would be reduced to 80 decibels for the
wearer.
Cost:
Hearing protection devices do not have to be expensive to
work well or be comfortable. Expandable foam ear plugs are
available for about $1; muffs about $15-$30, depending on
quality.
As
with most personal protective devices, HPDs have limitations.
Improperly worn HPDs may not reduce the noise levels to within
acceptable levels and tend to cause a false sense of security.
Wearing both plugs and muffs at the same time will reduce the
amount of noise exposure. However, the additional reduction
from wearing both devices will be only 6 or 7 decibels, even
if the NRR for both devices is above 25.
A dirty
HPD can cause serious skin irritation and ear infection. Follow
manufacturer's instructions to clean non-disposable HPDs,
and keep in a clean, dry container. Washing expandable foam
or disposable plugs can actually harbor germs and foster disease.
Wearing
hearing protection devices may take some adjustment. At first,
wearers may experience some physical discomfort after several
hours. Upon continued use, these annoyances generally diminish.
The long-term benefits -- diminished loss of hearing -- outweighs
any short-term inconveniences from wearing HPDs.
How
Much Do You Know?
- Most
hearing protection devices, regardless of type or design,
reduce about the same amount of noise that reaches the ear.
True or false?
- An
extended time in a noisy environment can make people feel
anxious and fatigued. True or false?
- The
squeal of a pig has a louder decibel level (sound) than
a rock concert. True or false?
- Which
of the following sounds could cause hearing loss?
- an
electric drill
- a
garden tractor
- an
enclosed poultry building
- all
of the above
- It's
more difficult to hear conversations in a noisy environment
while wearing a hearing plug or muff. True or false?
- Hearing
muffs always block out more noises than hearing plugs. True
or false?
See
answers at the end of "What Can You Do?".
What
Can You Do?
- Identify
jobs where the noise may be harmful to your hearing or bothers
you.
- Ask
your local farm supply dealer to stock HPDs.
- Wear
hearing protection in any situation in which you must raise
your voice to be heard 3 feet away.
- Get
a hearing test if you think you may have hearing loss or
question your hearing ability.
- Purchase
a hearing protection device that will meet your specific
needs. Follow the manufacturers' instructions for proper
use and wear.
Answers
to quiz:
1-False;
2-True; 3-True; 4-d; 5-False; 6-False
If
you're interested in purchasing a hearing protection device,
check with your local farm supply store or a direct-mail catalog.
An audiologist or hospital clinic also would be a good source.
For more information about hearing protection devices, contact
the National Safety Council (NSC) for a copy of a Rural Accident
Prevention Bulletin: Hearing Protection in Agriculture, Catalog
#69941-0006. You can write the NSC at 444 N. Michigan Avenue,
Chicago, Illinois 60611. Cost is about $1.
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
This
document is Fact Sheet
Pm-1518j
,
a series of the Safe Farm Program, Iowa State University Extension,
Ames, Iowa. Safe Farm promotes health and safety in agriculture.
It is funded by the National Institute for Occupational Safety
and Health, Iowa State University, and a network of groups that
serve Iowa farm workers and their families. Publication date:
October 1993.
Prepared
by Dennis Zeimet, industrial education and technology; Charles
V. Schwab, extension safety specialist, and Laura Miller,
extension communications. Design by Valerie King, Iowa State
University Extension, Ames, Iowa.
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