2. The Effects of Noise on
Hearing
Continuous exposure to excessive levels of
noise may cause irreversible hearing loss.
Such loss is exhibited by a shift in the ear’s
ability to perceive audible sound.
Initially, brief noise exposure may cause a
temporary decrease in hearing sensitivity,
that typically returns to its former level within
a few minutes to a few hours.
Repeated exposures lead to a permanent
threshold shift, an irreversible hearing loss.
3. What’s the purpose of
hearing protection?
When properly used, hearing
protectors can lower your noise
exposure below 85 decibels where it
will not cause hearing loss.
4. Types of Hearing Protection
Each type of hearing protection offers a
potential reduction of noise called the Noise
Reduction Rating (NRR). The NRR for
each type of hearing protection will be
printed on the package.
They types of hearing protection available
at Calvin are:
• Ear Plugs
• Formable Plugs
• Premolded Plugs
• Ear Muffs
5. Advantages and Disadvantages
EAR PLUGS
Advantages:
Inexpensive
Convenient
May be worn with
other PPE
Universal Fit
Disadvantages:
Poor Sanitation
Easily worn
incorrectly
Difficult to use when
cold
May contribute to
ear infection
6. Advantages and Disadvantages
EAR MUFFS
Advantages:
Convenient
Complete ear
protection
Reusable
Disadvantages:
Hot
Fit is affected by
other PPE
Less comfortable
Size
7. Selection
Hearing protectors can be very effective but
only if they fit properly and are worn
correctly.
The more carefully you select and wear
hearing protectors, the higher your
protection will be.
Hearing protectors may feel uncomfortable
at first, but give yourself a chance to get
used to them, just as you do with a new pair
of shoes or glasses.
8. Earplugs
Formable Plugs
Fit: One size fits most. Foam plugs gently expand to
provide a snug and secure custom fit.
Use: Slowly roll and compress foam plugs into a very
thin cylinder. While compressed, insert plug well into
the ear canal.
Maintenance: Keep plugs clean and free from material
that can irritate the ear canal. Discard plugs if they
harden or do not re-expand to their original size and
shape.
9. Earplugs
Premolded Plugs
Fit: Premolded plugs are made from flexible materials
which are preformed to fit the ear. Most premolded
plugs are sold in two or more sizes and must be
individually sized for each ear.
Use: Reach around the back of you head and pull
outward and upward on the ear while inserting the plug
until you feel it sealing.
Maintenance: Premolded plugs will normally last
several months. They should be replaced if they
shrink, harden, tear, crack, or become permanently
deformed. Wash them in warm soapy water and rinse
well. When dry store in a carrying case.
10. Earmuffs
Fit: Earmuffs have rigid cups with soft plastic cushions
which seal around the ears to block noise.
Use: Muffs must fully enclose the ears to seal against
the head. Adjust the headband so cushions exert
even pressure around the ears to get the best noise
reduction. No hair should be beneath the cushion.
Maintenance: Cushions can be cleaned with warm
soapy water and rinsed thoroughly. Do not use
alcohol or solvents. Cushions need replacing
whenever they become stiff, cracked or do not seal.
Don’t modify earmuffs in any way, and especially do
not stretch or abuse the headbands as this will reduce
your protection.
11. Rules of thumb
When either a plug or muff is properly fitted,
the sound of your own voice should change,
becoming deeper, hollow or muffled. If you
don’t hear the change, or if it isn’t the same
in both ears, you haven’t obtained a proper
fit and acoustic seal in either one or both
ears.
When you feel the need to shout in order to
be heard three feet away, the noise levels
are probably 85 dBA or more and hearing
protectors are recommended.
12. Audiometric Testing
Audiometric testing measures your ear’s
ability to pick up different frequency sounds.
This is the best way to check if any of your
hearing cells are no longer picking up
sound.
Hearing loss is a slow, gradual process and
this test can pick up changes that you may
not have noticed.
13. Audiometric Testing Cont.
If you having measurable hearing loss, this
is called Standard Threshold Shift (STS).
This measurable loss can be caused by a
number of things such as a head cold,
listening to loud music, working without your
earplugs, etc.
Audiometric testing is required for all Calvin
employees whose job may expose them to
noise levels at or above 85 decibels.
14. Audiometric Testing Cont.
A second test is performed within 3
weeks if any STS is picked up during
your initial test.
It is generally best to do the testing
before you begin your work.
15. What is Audiometric Testing?
You will be asked not to expose yourself to loud noise
for 14 hours prior to test. If you are to tested after you
been at work you must wear hearing protection prior to
the test.
You will be seated in a sound proof booth and will be
given headphones.
The audiometric technician will ask you to signal when
you hear different tones.
Tests will be separate for each ear and for different
frequency ranges.
The test takes about 10 minutes.
16. What is Audiometric
Testing? (Cont.)
The results of the test show how you
were able to detect the different
frequency sounds in the test.
Your annual audiogram will be
compared to your previous test results
and maintained in your employee file.
