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Michigan Mine Safety & Health Training Program
Noise Monitoring & Your Hearing
Conservation Program
Monitor noise exposure at your Mine site using a
Sound Level Meter or Dosimeter, and develop a
Hearing Conservation Program,
Michigan Mine Safety & Health Training Program
Michigan Mine Safety & Health Training Program
Introduction
30 CFR Part 62 is the new MSHA Noise Standard. The
following presentation provides current information on this
regulation, and is based on material that was presented to
Michigan mine operators in hands-on noise sampling
workshops in 2001.
No specific claims are made concerning the accuracy of the
information presented here.
Michigan Mine Safety & Health Training Program
Printed Materials Needed for this Presentation.
 Printed Materials
• There are hardcopy forms, tables and examples that go with
this presentation. Make sure they are available.
• Please note that the MSHA Noise standard does not dictate the
format of forms. The forms presented here are suitable for
recording purposes, but you may design your own.
 The Printed Materials we've provided have been
numbered in the order that they are presented.
• Form numbers are in the upper right-hand corner of the form.
• Some forms consist of more than one page.
Michigan Mine Safety & Health Training Program
Minimum Equipment Needed for this Presentation.
 A slow-response 'A' scale Sound Level Meter (SLM)
• Make sure you have the manufacturer’s instructions.
• SLMs may be purchased for as little as $40 from electronics
stores.
 Field Calibrator for the SLM
• Instrument Calibrators confirm the accuracy of readings.
Michigan Mine Safety & Health Training Program
Other Equipment Included in this Presentation
 Dual-Threshold Dosimeter
• Simultaneously measures Action Level & PEL noise
doses.
• Must be able to be set to slow response on the 'A' scale.
(This is the default setting for most dosimeters.)
• Field Calibrator for Dosimeter.
Michigan Mine Safety & Health Training Program
Purpose of this Presentation
Objectives
• To provide you with basic Noise Hazard Information
• To show you how to do proper Noise Sampling, Noise
Dose Calculation, and Record Keeping.
• To prepare you to administer a Hearing Conservation
Program (HCP) meeting MSHA's requirements.
Regulations of Concern
• Noise Sampling - CFR 30 § 62.110
• Hearing Conservation Program - CFR 30 § 62.150
Michigan Mine Safety & Health Training Program
Noise Basics
 The two factors that determine how hazardous noise
is are:
• Intensity (Loudness) measured in dBA
• Time of Exposure measured in Hours and Minutes
 The louder the noise, the more hazardous it is. Also,
the longer the exposure time, the more hazardous
the noise is.
 A “Noise Dose” combines both loudness and time
and is a convenient way of describing the relative
hazard of the noise.
Michigan Mine Safety & Health Training Program
Noise Basics
Loudness is measured using a logarithmic scale. This
means that a 10 decibel increase does not simply add 10
to the previous level. It multiplies the previous level by 10.
Threshold of Hearing
Quiet Room
Conversation
Car (50 mph at 50 ft)
End Loader (In Good Cab)
Haul Truck (In Good Cab)
Crusher
Old Dozer (No Cab)
Air Track Drill (No Controls)
0 dBA
45 dBA
55 dBA = 45 dBA x 10
65 dBA = 45 dBA x 100
75 dBA = 45 dBA x 1,000
85 dBA = 45 dBA x 10,000
95 dBA = 45 dBA x 100,000
105 dBA = 45 dBA x 1,000,000
115 dBA = 45 dBA x 10,000,000
115 dBA has 10 million times more sound energy than 45 dBA and is
capable of causing 10 million times more damage to hearing.
Michigan Mine Safety & Health Training Program
Noise Basics
Allowable Noise exposure is based on Noise Dose.
Noise Dose is expressed as a percentage of the allowable
limit. How high it goes depends on both noise intensity
and time of exposure to noise.
Louder (More dBA) = More Noise Dose
Longer (More Time) = More Noise Dose
Absolute Quiet = 0% Noise Dose.
85 dBA for 8 Hrs = 50% Noise Dose.
90 dBA for 8 hrs = 100% Noise Dose.
95 dBA for 8 Hrs = 200% Noise Dose.
95 dBA for 12 Hrs= 300% Noise Dose.
Michigan Mine Safety & Health Training Program
Noise Basics
Different combinations of Loudness and Time can
produce the same Noise Dose. The following
combinations can all produce about 75% Noise Dose.
84 dBA for 14 Hrs = 76%
85 dBA for 12 Hrs = 75%
87 dBA for 9 Hrs = 74%
88 dBA for 8 Hrs = 76%
93 dBA for 4 Hrs = 76%
95 dBA for 3 Hrs = 75%
98 dBA for 2 Hrs = 75%
103 dBA for 1 Hr = 76%
108 dBA for 30 Min = 76%
113 dBA for 15 Min = 76%
Note: this table is based on using the 80 dBA (Low) threshold.
Michigan Mine Safety & Health Training Program
Noise Dose Table
For the next several slides, refer to the Noise Dose
Table in your printed materials. This is Table 1.
A Noise Dose table is used to look up the Noise Dose
when 'noise-level & exposure-time' are known.
(Please note that the table shown in the following
slides are not an exact duplication of the real Noise
Dose table.)
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Exposure Time
Exposure times (in Hours) are listed across the top of
the table. (Shown here in red.)
N
O
I
S
E
L
E
V
E
L
I
N
d
B
A
Exposure Time (Hours)
.25 .5
85
86
87
88
89
90
91
92
93
94
95
1
2
3
4
5
6
7
8
9
10 11 12
Michigan Mine Safety & Health Training Program
Noise Levels
Noise Levels (in dBA) are listed down the left side of the
table. (Shown here in green.)
N
O
I
S
E
L
E
V
E
L
I
N
d
B
A
Exposure time in Hours
.25 .5
85
86
87
88
89
90
91
92
93
94
95
1
2
3
4
5
6
7
8
9
10 11 12
Michigan Mine Safety & Health Training Program
Estimating a Noise Dose Using the Table
1. Measure the Decibel Level. (We will discuss methods for doing this later.)
2. Measure or estimate Exposure Time.
3. The Noise Dose is found at intersection of Decibel
Level and Exposure Time. (Yellow Box)
N
O
I
S
E
L
E
V
E
L
I
N
d
B
A
Exposure time in Hours
.25 .5
85
86
87
88
89
90
91
92
93
94
95
1
2
3
4
5
6
7
8
9
10 11 12
Noise Dose for
92 dBA for 6
hours
Michigan Mine Safety & Health Training Program
Using Noise Dose Table if Noise Levels vary.
1. If Noise Levels vary, divide shift into separate tasks.
2. Determine Dose for each task, then add the doses.
N
O
I
S
E
L
E
V
E
L
I
N
d
B
A
Exposure time in Hours
.25 .5
85
86
87
88
89
90
91
92
93
94
95
1
2
3
4
5
6
7
8
9
10 11 12
Michigan Mine Safety & Health Training Program
REVIEW
1. Loudness is measured in dBA
Quiet Room = 45 dBA
Crusher = 95 dBA
Air Track Drill = 115 dBA
2. Noise Dose = Loudness + Exposure Time
Quiet (45dBA)for 8 Hrs = 0% Noise Dose
Crusher (95dBA) for 8 Hrs = 200% Noise Dose
Air Track Drill (115dBA) for 8 Hrs = 3,200% Noise Dose
(The dBA level alone does not define noise hazard!)
4. Use Noise Dose Table to determine the hazard.
5. Noise Dose defines the noise hazard.
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Noise Table Exercises
(Answers on next slide.)
Use the Noise Dose Table to figure out the Noise
Dose for the following conditions:
1) Noise exposure is 88 dBA for 10 Hr
What is Noise Dose ?
2) Noise exposure is 84 dBA for 4 Hrs and 94 dBA for
6 Hrs. (Remember: Figure the two noise doses
separately and then add them.)
What is the total Noise Dose ?
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Noise Table Exercises - Answers
1) 88 dBA for 8 hours = 95% Noise Dose
2) 84 dBA for 4 hours, plus 94 dBA for 6 hours = 152%
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Noise Table Exercises
3) Noise exposure is 79 dBA for 2 Hrs, 92 dBA for 3
Hrs, 81 dBA for 3 Hrs, 87 dBA for 30 Min, 90 dBA
for 1 Hr, and 82 dBA for 30 Min.
What is Noise Dose ?
Michigan Mine Safety & Health Training Program
Noise Table Exercises - Answer
Answer to Exercise 3
79 dBA is under 80 dBA and is not counted toward
the Noise Dose. The Noise Dose is obtained by
adding the rest of the calculated doses is 79%.
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Time Weighted Average (TWA8)
The 'TWA8' is the Noise Level (dBA) which, if constant
over 8 hours, would result in the same Noise Dose as
the one calculated using the actual exposure time.
Example:
If a worker's Noise Dose from a 10 hour shift is 400%,
what constant Noise Level (in dBA) over 8 hours would
produce the same Dose?
The answer is on the Noise Dose Table.
Find "400" in the the "8 hour" Exposure Time column.
Follow the row left to the Noise Level, which, in this
case, is 100 dBA.
The TWA8 value for any Noise Dose equaling 400% is
100 dBA .
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Time Weighted Average (TWA8) - Continued
Why use TWA8? Why not just use Noise Dose.
Because the "TWA8" (which is expressed in dBA,
rather than a percentage) is easier to use when applied
to noise controls.
Example: If one knows that the noise level in an area is
kept below 90 dBA, for the full 8 hour work shift, then
the 90dBA PEL has not been exceeded. Trying to think
of this in terms of percentages is awkward.
Action Level = 85 dBA (TWA8)
Permissible Exposure Limit = 90 dBA (TWA8)
Double Hearing Protection Level = 105 dBA (TWA8)
Michigan Mine Safety & Health Training Program
Noise Sampling And Hearing
Conservation Program
To obtain the full benefit of this section, make sure
any noise sampling equipment you have is at hand.
Michigan Mine Safety & Health Training Program
§ 62.110 - Noise Exposure Assessment
“The mine operator must establish a system of monitoring
that evaluates each miner’s noise exposure sufficiently
to determine continuing compliance with this part.”
Note that 'monitoring' is not the same thing as 'sampling'.
Self-sampling is only one of several types of 'monitoring'
allowed by the standard. Other types of monitoring can
include the following:
1. MSHA compliance sampling. (MSHA does the sampling.)
2. Equipment Manufacturer Specifications. (The equipment
manufacturer does the sampling.)
Regardless of the method, adequate records must be kept
to prove that monitoring is being done.
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How Often Is Noise Sampling Required ?
 There is no mandatory sampling schedule. However,
employee noise exposure records must accurately
reflect the current noise conditions at the mine.
 The mine operator must decide whether existing
records (Self sampling, MSHA sampling, Manufacturer
Specs., etc.) reflect current conditions.
• If noise exposure has not changed, further sampling may not
be needed.
Michigan Mine Safety & Health Training Program
Noise Sampling
Two types of instruments commonly used for
measuring noise are:
 Sound Level Meter (SLM)
• Cost as low as $40. Takes single noise
measurements. (Because of this, a great deal of
work must be done to calculate Noise Doses.)
 Noise Dosimeter
• High-cost instrument ($2000 and up). Takes
measurements constantly and does all the work of
calculating Noise Dose.
 Your printed documentation includes detailed sampling checklists
for both an SLM and a Noise Dosimeter.
Michigan Mine Safety & Health Training Program
Sound Level Meter (SLM)
Sound Level Meter (SLM)
•
•
•
•
•
Only gives instantaneous Noise Level readings.
The readout is in dBA.
Normally used to spot check Noise Levels.
Can be used to determine Noise Dose (with calculations).
The accuracy is ± 2 dBA.
Readings tend to err on the low side. Add 2
dBA to SLM readings before recording them.
Always read manufacturers instructions for
proper SLM operation.
Michigan Mine Safety & Health Training Program
Dosimeter
Always be familiar with manufacturer's instructions for proper operation.
A typical dosimeter is usually capable of displaying the following information:
•
•
•
•
•
•
•
•
•
•
•
Run Time From Start Of Sampling
Low Threshold (Action Level) Noise Dose
Low Threshold Average Noise Level
High Threshold (PEL) Noise Dose
High Threshold (PEL) Average Noise Level
Sound Level Meter (Readout in dBA)
Maximum Noise Level Over A 1-Second Period
Time After Start Of Sampling When Max 1-Second Noise Level Occurred
Maximum Noise Level Over 1/16 Second Period
Projected 8-Hr Noise Dose
Time After Start Of Sampling When Noise Level Greater Than 115 dBA
Occurred
Michigan Mine Safety & Health Training Program
SLM Exercise 1- Calibration
For these Exercises you will need a calibrator. This can be either be
a single or a multiple noise level calibrator. You will also need your
Sound Level Meter (If you have a Dosimeter, switch it to SLM mode.)
1. Insert instrument microphone into the calibrator.
2. Turn on instrument and set it to read on the 'A scale'
and at the 'slow response' setting. If you are using a
dosimeter, switch it to Sound Level Meter (SLM) Mode.
3. Turn the calibrator to the lowest dB level. What is the
Noise Level ? Your instrument should read within ± 1
dBA of the level indicated on the calibrator.
4. If your calibrator is a multi-noise level calibrator,
repeat the above step for all noise levels on the
calibrator.
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SLM Exercise 1- Calibration Continued
You have just calibrated your Sound Level
Meter.
Calibrate your instrument whenever you do
noise sampling.
One Pre-Sampling Calibration and One PostSampling Calibration per day is acceptable.
If the SLM readout is within ± 1 dBA of
calibrator setting, then instrument is reading
accurately.
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SLM Exercise 2 - Proper fit
1. Turn the calibrator on (Any Noise level will do).
2. Leave microphone in the calibrator
What is the Noise level?
It should be within 1 dBA of Noise level indicated on the
calibrator.
3. With the calibrator on, slowly remove the microphone.
What happens to the Noise level?
It should drift down. This illustrates the need for a proper fit
between the calibrator and instrument. Calibrators are
usually designed to be used with only one type of
instrument. Some calibrators come with special collars or
fittings that allow them to be used with different instruments.
4. Always follow the calibrator manufacturer's recommendations.
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Using A Sound Level Meter (SLM)
1. Set the SLM to read on the 'A' scale at 'Slow Response'.
2. Always put the windscreen over the microphone. Wind noise can
seriously effect accuracy. Windscreens are precision manufactured
from special materials. Do not use a substitute.
3. If the needle (analog readout) or the number (digital readout) is
bouncing on the SLM, take the highest value as your official
reading.
4. Add 2 dBA to this value before recording it.
5. Take frequent measurements at different times of the day, and
whenever the task or the noise exposure changes.
6. Hold SLM at arm’s length away from your body. Point the
microphone up. Do not place your body between the SLM and the
noise source and, do not place the SLM between your body and the
noise source.
7. If measuring personal exposure, hold SLM next to subject’s ear on
the “Noisiest” side.
8. Document, Document, Document
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SLM Documentation Forms
 Your printed material includes SLM documentation
forms. (See Blank Forms 1.1 thru 2.2, and filled out
Example Forms 3.1 thru 6.2)
 Always record your name, date, location, time, noise
sources, noise controls, work activity, SLM data, and
calibration.
 If you are simply spot checking noise levels, you can
record this information on Table A of Form 1, and
nothing further need be done.
 If you are measuring personal noise exposure, you
must:
• Complete Table A on Form 1.1, 1.2
• Complete Table B on Form 1.2
• Complete Entire Form 2 (both 2.1 and 2.2)
 Instructions for filling out forms are on the forms.
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SLM Documentation - Sample Forms 3.1, 3.2
Loader Operator
 Note that in table A, fractional dBA’s are rounded up to
the next whole number.
 Note the number of sound level readings taken and
the accompanying activity documentation.
 The more thoroughly you document the monitored
activity, the more accurate will be your final estimate
of noise exposure.
 Measure often.
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SLM Documentation - Sample Form 3.2
Loader Operator - Continued
Go to Table B On Form 3.2. The estimated total shift times spent at
various noise levels are recorded here. Note that any readings from
Form 3 that were below 80 dBA were not counted.
Noise Level
Total Estimated Shift Exposure time
80 dBA ……………………...……..1 hr.
83 dBA (1:00 + 2:00 + 3:00)……. 6 hr.
84 dBA ……………………...……..1 hr.
85 dBA ……………………...……..1 hr.
Remember: The more measurements made, the more accurate the
estimates.
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SLM Documentation - Sample Forms 5.1, 5.2
Crusher Operator
In this example, the job of Crusher Operator is
more complex than the Loader Operator.
Therefore, it is even more important to
measure often and thoroughly document the
activity. (Table A)
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SLM Documentation - Sample 1b Continued
Crusher operator - Continued
Go to Form 5.2, Table B. The estimated total
shift time at the various as noise levels are
recorded as follows.
Noise Level
Total Shift Exposure Time
83 dBA for 2:15 ………………………….rounded up to 3:00
84 dBA for 1:15 + 1:00 + 3:50 ...……….6:00
87 dBA for 0:15 ………………………….0:15
92 dBA for 0:45 + 0:40 ..………………..rounded up to 2:00
112 dBA for 0:03 ...………………………rounded up to 0:15
Michigan Mine Safety & Health Training Program
Figuring the Noise Doses from SLM Data
How much noise is “TOO MUCH” ?
Two Noise Limits are defined in the Part 62 Noise Rule:
• Action Level (AL)
• Permissible Exposure Limit (PEL)
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New Noise Rule - Action Level
The minimum Noise Dose at which you must take action.
The Action Level is defined as a 50% Noise Dose
(using the 80dBA Low Threshold instrument setting),
which is equal to a TWA8 of 85 dBA
The Action Level Noise Dose includes the all noise
between 80 dBA and 130 dBA called the Low Threshold
Noise Dose.
If a miner's Noise Exposure over an entire work shift
equals or exceeds the 50% Action Level, the miner
must be enrolled in the company's Hearing
Conservation Program as per §62.150
Michigan Mine Safety & Health Training Program
New Noise Rule - Permissible Exposure Limit
Permissible Exposure Limit (or PEL) is defined as a 100%
Noise Dose, which is equal to a TWA8 of 90 dBA.
The PEL Noise Dose includes all noise between 90 dBA
and 140 dBA This is called the High Threshold Noise
Dose.
If a miner's exposure exceeds the PEL :
 Feasible engineering and administrative controls must
be applied.
 The miner must enroll in the company's Hearing
Conservation Program as per §62.150.
 Double hearing protection must be worn if Noise Dose
is higher than 800% (where the TWA8 = 105 dBA.)
 No exposures above 115 dBA are allowed (based on a
30 second average reading.)
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Sampling for the Action Level and the PEL
 Sampling must include Action Level Noise Dose AND
PEL Noise Dose.
 The Action Level Noise Dose must include all noise from
80 dBA to 130 dBA (80 dBA Threshold).
 The PEL Noise Dose must include all noise from 90 dBA
to 140 dBA (90 dBA Threshold)
 For a Sound Level Meter, use the Noise Dose Table. (For
the PEL use only the Noise Level values above 90 dBA.
The Action Level uses the entire chart.)
 If you have a Dosimeter, it must be capable of doing
measurements for both PEL and AL.
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Figuring Noise Doses
Forms 2.1 & 2.2 are the blank SoundLevel-Meter Noise Dose calculation
forms.
See Loader Operator example - Forms
4.1/ 4.2.
The estimated exposure times at various
decibel levels from form 3.1 have been
transferred to the appropriate spaces on
Forms 4.1/4.2
The same has been done for the Crusher
Operator on Forms 6.1/6.2.
Michigan Mine Safety & Health Training Program
Noise Doses for the Loader Operator
The Noise Dose Table is then used to figure
the Noise Dose for each Noise Level. This
Noise Dose is then recorded in the third
column of Forms 4.1/4.2 for the Loader
Operator (forms 6.1/6.2 for the Crusher
operator.)
When you are calculating your own Noise
Doses, follow the same steps as these
examples.
Finally, add all the separately calculated Noise
Doses to get the final Noise Dose for the full
work shift.
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Dosimeter Sampling
Noise Dosimeters:
• Measure accumulated exposure to varying noise
levels over time period.
• Give readouts in % Noise Dose.
 Most Dosimeters also provide:
• Sound Level Meter (SLM) capability.
• Average Noise Level. (Time Weighted Average)
• Projected 8 Hr Noise Dose.
Michigan Mine Safety & Health Training Program
Dosimeter Exercise #1
This exercise illustrates how quickly the noise dose can
accumulate at high noise levels.
1. Insert microphone into calibrator.
2. Turn on dosimeter.
3. Set calibrator to 124 dB (or as high as it will go).
4. With dosimeter set to display High-Threshold Noise Dose
%, turn the calibrator on for exactly 5 minutes.
5. While waiting, watch how fast the Noise Dose is adding
up. (Note:Some dosimeters may require you to press the
'Noise %' button continuously to get a running readout.)
6. Turn the calibrator off after 5 minutes.
7. The Noise Dose would be somewhere around 125% for a
calibrator set to 124 dB and 17% for a calibrator set to
110 dB.
Michigan Mine Safety & Health Training Program
Dosimeter Exercise #2
This exercise demonstrates the ability of a dual-threshold dosimeter to
distinguish between Low Threshold and High Threshold Noise Doses.
1. Write down the High Threshold Noise dose you obtained from the
previous exercise. (Do not clear or reset the dosimeter.)
2. Leave microphone in the calibrator and switch the dosimeter display
to SLM.
3. If calibrator is multi-level, turn calibrator to the lowest dB setting.
4. Slowly remove the microphone until the dosimeter display reads 83
dB.
5. Try to hold the microphone in this position for exactly 5 minutes.
6. Switch the dosimeter display back to High Threshold Noise Dose %.
There should be no increase in the Noise Dose % because the noise
being measured is below the High Threshold Limit of 90 dBA.)
7. Now, switch the dosimeter display to Low Threshold Dose %. This
reading should be slightly higher than the High Threshold Noise Dose
because the noise being measured is above the Low Threshold Limit
of 80 dBA.
Michigan Mine Safety & Health Training Program
In Review
Dosimeters are “Dual Threshold”
The Noise Dose is accumulated
simultaneously at both 80 dBA and 90 dBA
thresholds:
• 80 dBA is the threshold for the “Action
Level”
• 90 dBA is the threshold for the “PEL”
Michigan Mine Safety & Health Training Program
Noise Sampling with a Dosimeter
1. Make sure the microphone is inserted into the
Windscreen.
2. Clip the dosimeter to the subject’s belt, or put it in the
subject's pocket.
3. Clip the microphone to the center of the shoulder,
pointing up. (Pick the subject's “Noisiest” shoulder.)
4. If necessary, use clips or duct tape to attach the
microphone cord to the clothing.
5. Document, Document, Document
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Dosimeter Documentation - Form 7
 Always record your Name, Date, Employee Name,
Location, Time On, Time Off, Noise Sources, Noise
Controls, Work Activity, Hearing Protectors, Dosimeter
Data, and Calibration
• Throughout the sampling period, record the
accumulated Noise Dose as often as the task
changes or at least every 2 hours if the task does not
change.
• Spot check the Noise Levels with an SLM (to verify
Dosimeter readings).
• Record the Final (or Projected) Noise Dose.
Michigan Mine Safety & Health Training Program
Projected Noise Dose
 You can sample for less than 8 hrs, and the dosimeter will calculate
what an 8 hr exposure would be if the noise had continued at the
same average level.
 This is called the Projected Noise Dose.
 It is less accurate than sampling for a full 8 hours.
 It does not project for 10 hr, 12 hr, or 14 hr, etc. work shifts. These
you must estimate yourself or sample the entire shift.
Projected Noise Dose Exercise:
 Place the microphone in the calibrator.
 Turn on the dosimeter and the calibrator.
 Switch dosimeter to 'Projected 8 hour Noise Dose'.
 Depending on the Noise Level that the calibrator is set at, you will
now get an 8 hour projected estimate of the Noise Dose for that
Noise Level.
Michigan Mine Safety & Health Training Program
Noise Sampling - General Sequence
Pick your sampling method. (SLM, Dosimeter,
or both.)
Pick individuals, tasks, or areas to be sampled.
Conduct the sampling.
Observe the employees sampled & document
these observations.
• Record SLM readings at various worker locations
and note time worker spends at each location.
Evaluate the sampling results.
If necessary, control exposure.
See Noise Checklist in your written material.
Michigan Mine Safety & Health Training Program
Interpretation of Noise Sampling Results
Every noise measurement involves error related
to the accuracy and precision of the sampling
instrument (dosimeter or SLM).
Most dosimeters and SLMs are accurate to ± 2
dBA.
For an SLM reading to be on the safe side, add
2 dBA to all measurements when you record
them.
For a dosimeter, multiply final end-of-shift
measurement by 1.32 to get final Noise Dose.
• Example: If the end of shift Noise Dose Reading is 87, multiply this by
1.32 and round the results up to the nearest whole number. In this case
it would be 115.
Michigan Mine Safety & Health Training Program
Interpretation of Noise Sampling Results
If the Action Level Noise Dose (i.e. the Low
Threshold Noise Dose) is less than 50%:
• No action necessary
• Continue to maintain noise controls
• Spot check levels from time to time
Michigan Mine Safety & Health Training Program
Interpretation of Noise Sampling Results
If the Action Level Noise Dose is equal to, or
greater than 50%:
• You must enroll all effected employees in
the company's hearing conservation
program.
• Review noise controls. (You may wish to
upgrade controls, but it is not required.)
• Spot check Noise Levels from time to time.
Michigan Mine Safety & Health Training Program
Interpretation of Noise Sampling Results
If the PEL Noise Dose (High Threshold Noise
Dose) is 100% or more:
• You must enroll the affected employees in
the company's HCP.
• You must require Hearing Protectors.
• You must implement feasible engineering &
administrative controls to reduce noise
exposure.
If the PEL Noise Dose is more than 800%, dual
hearing protectors (Muffs & Plugs) are required.
No employee can be exposed to 115 dBA for
any length of time. MSHA issues a citation for a 30-second
slow response average reading greater than or equal to 117 dBA.
Michigan Mine Safety & Health Training Program
Hearing Conservation Programs
At the Action Level, Hearing Conservation
Program enrollment becomes mandatory, not
voluntary!
See examples of Hearing Conservation
Program Forms in your printed material.
• Hearing Conservation Training Program Record
Forms 8 or 9. (Records Hearing conservation
Training.)
• Hearing Conservation Program Employee
Enrollment Record - Form 10 (Lists dates when all
the various aspects of an HCP are completed.)
Michigan Mine Safety & Health Training Program
Hearing Conservation Programs
 MSHA’s HCP rules are similar to OSHA’s, except that
MSHA doesn't require a written program.
 An HCP MUST include the following five elements, as
per CFR 30 §62.150:
• System of noise monitoring
• Provide hearing protectors
• Audiometric testing
• Hearing conservation training
• Record keeping
The HCP must not cost the employee any
money or time.
Michigan Mine Safety & Health Training Program
System of Noise Monitoring - Methods
 The monitoring method is not specified in the
MSHA standard (§62.110), therefore:
• Your own SLM or Dosimeter may be used.
• MSHA compliance sampling data may be used.
• Equipment manufacturer's noise specifications may be
used.
 Whatever the monitoring method used, the data it
generates must represent full shift exposure.
 Employees may observe monitoring, however, the
company does not have to pay a worker for this
activity.
 Employee notification is required if the noise
exposure equals or exceeds the Action Level. (See
example of Notification Letter in your printed
materials.)
Michigan Mine Safety & Health Training Program
System of Noise Monitoring - Records
 Noise monitoring records may be requested by an
inspector during an MSHA inspection
 In your printed materials there is an example of a form
entitled "Employee Noise Exposure Record".
 Part 62 does not specify the record-keeping format. The
forms provided here are an example of what you might
3” x 5”
use to show MSHA that you are, indeed, monitoring
File Card
your employees for noise exposure.
Action Level Noise Dose
PEL Noise Dose
Enrolled in HCP? No•
%
%
Yes
•
Date
Michigan Mine Safety & Health Training Program
Providing Hearing Protectors
 A mine operator must provide Hearing Protectors if a
worker's noise exposure is at or above the Action
Level. (as per §62.160)
• The employee must be given a choice of 2 different types of
ear muffs and 2 different types of ear plugs.
• The employee must be provided additional choices if a
medical condition prevents the use of the original choices
offered initially.
• Hearing protectors must be in good condition and must be
fitted properly.
 Operator must require the use of hearing protectors if
noise exposure exceeds the PEL, if audiometric
testing shows a Standard Threshold Shift, or if
audiometric testing will be delayed for more than 6
months after high noise levels are measured.
Michigan Mine Safety & Health Training Program
Audiometric Testing
As per MSHA regulations §62.170 through §62.175
 Audiometric testing must be offered to employees if
their exposure is at or above the Action Level.
 The law allows employees to choose whether to submit
to audiometric testing if it is something the company
has not made mandatory.
 Baseline audiometric testing must be provided within 6
months of enrollment in the HCP (12 months if mobile
lab is used.)
 Annual audiometric testing must be offered thereafter
on employees who were baseline tested.
 Two Forms "Record of Baseline Audiometric Testing",
"Record of Annual Audiometric Testing" are provided in
your printed material.
Michigan Mine Safety & Health Training Program
Audiometric Testing
What is it?
Why do it ?
 An Audiometric test is a standardized method to
measure hearing sensitivity at various sound
frequencies.
 Changes in sensitivity can indicate a hearing
impairment.
 Audiometric testing does not prevent hearing loss.
 A standard threshold shift in a worker's hearing
sensitivity should trigger a management response
(training, job change, hearing protectors, etc. ) to
prevent further hearing loss.
Michigan Mine Safety & Health Training Program
Audiometric Testing - Results
 Reportable Hearing Loss.
• This is a hearing loss relative to the worker's baseline audiogram
(or upward revised baseline).
• It is a 25 db average change for the worse in either ear at 2000,
3000, and 4000 hertz.
• This hearing loss must be reported on the MSHA Accident form
7000-1
 Standard Threshold Shift.
• This is a hearing loss relative to the baseline audiogram (or
upward revised baseline)
• It is a 10 db average change for the worse in either ear at 2000,
3000, and 4000 hertz.
• An employee shown to have a Standard Threshold Shift (STS)
must be retrained and offered hearing protection by the company
if the audiologist determines the STS to be work related. The
company must review the effectiveness of engineering and
administrative noise controls.
Michigan Mine Safety & Health Training Program
Example Baseline Audiogram
125
250
500
1K
2K
10
0
10
20
30
40
50
Baseline Audiogram
(The initial audiogram
taken by worker when
first employed.)
3K
4K
6K
8K
Michigan Mine Safety & Health Training Program
Annual Audiogram (Showing STS)
125
250
500
1K
2K
3K
4K
6K
8K
10
0
BASELINE
10
16
20
30
40
50
16 + 9 + 8 = 33
33 / 3 = 11
Reportable Loss? NO
STS ?
YES
9
8
ANNUAL
Michigan Mine Safety & Health Training Program
Audiometric Testing
 As per MSHA regulation § 62.170
 The Standard doesn't mandate Audiometric testing,
but it must be offered to all employees enrolled in a
hearing conservation program. It can also be a
condition of employment required by the company.
 Audiometric testing is conducted by a physician,
audiologist, or qualified technician under the direction
or supervision of a physician or audiologist.
 A Qualified Technician means one that has been
certified by the Council for Accreditation in
Occupational Hearing Conservation (CAOHC), or its
equivalent. (20 hour course for certification.)
Michigan Mine Safety & Health Training Program
Hearing Conservation Training
 Per MSHA regulation §62.180
 Training must be provided within 30 days of enrolling in
HCP, and annually thereafter.
 This training may be combined with part 46/48 annual
refresher training.
 The training must include:
•
•
•
•
Effects of noise on hearing, hearing protectors, noise controls.
Requirements of MSHA’s Part 62 rule.
The operator and employee roles in noise control.
The value of audiometric testing.
 The mine operator must certify the training date & type.
 A sample record for recording HCP training is included
in your printed materials. Or, if this training is part of
your Annual Refresher training plan, it can be recorded
on your AR training certificate.
Michigan Mine Safety & Health Training Program
Record Keeping
 Records must be kept, and made available within 24
hrs of an MSHA request for records.
 Employees, employee rep’s, and former employees
also have access to these records under certain
conditions.
 Records required by part 62:
• Exposure monitoring (if at or above Action Level)
• Audiometric testing
• Training
 Records not required, but recommended:
• All exposure monitoring.
• The employee's choice of hearing protection.
• A signed statement from any employee who refuses
Audiometric Testing.