Title: Hearing Conservation Theresa Y. Schulz, PhD. Lt. Col. USAF (ret.)
1Hearing ConservationTheresa Y. Schulz, PhD.Lt.
Col. USAF (ret.)
2Topics
3Noise Acoustics
- Noise-Induced Hearing Loss
- Causes no pain
- Causes no visible trauma
- Leaves no visible scars
- Is unnoticeable in its earliest stages
- Accumulates with each overexposure
- Takes years to notice a change
4Noise Acoustics
Noise-induced hearing loss is the most common
permanent and preventable occupational injury in
the world.
World Health Organization
5Noise Acoustics
In many countries, excessive noise is the biggest
compensable occupational hazard. Cost of NIHL to
developed countries ranges from 0.2 to 2 of its
GDP. NIHL is on the rise globally. (Source WHO)
6Noise Acoustics
Most common occupational injury in the United
States. 22 million US workers are exposed to
hazardous noise at work on a daily basis. Approx.
8 million Americans suffer from NIHL. (Source
NIOSH, 2009)
7Noise Acoustics
Non-Occupational
Occupational
8Noise Acoustics
- Noise Measurement Devices
SOUND LEVEL METER Sound is measured immediately
in a specific area
PERSONAL DOSIMETER Sound averaged throughout
day for sample employee/job
IN-EAR DOSIMETER Collects
personal noise dose the only real measure of
risk
9NOISE AND ACOUSTICS Hierarchy of Controls
Noise Acoustics - Hierarchy of Controls
- ENGINEERING CONTROLS
- Buy Quiet
- Vibration Pads
- Enclosures
- Barriers
- Isolation
10NOISE AND ACOUSTICS Hierarchy of Controls
Noise Acoustics
Ototoxic Chemicals
- Ototoxic by themselves
- Synergistic effect with noise
- Large differences in sensitivity
- Recommend increased frequency of audiometric
testing
11Noise Reduction Rating(NRR)
12Hearing Protection Selection
Hearing Protection Selection Factors
13Noise Reduction Rating
Noise Level 100 dB Noise Reduction Rating
30 dB
- How much noise is reaching the ear of the worker ?
That is completely unknown
(55 104 dB)
140 dB
0 dB
33 dB
EAR 1
EAR 2
EAR 3
How much protection?
15Fitting Tips
Good Fit vs Bad Fit
16Noise Reduction Rating
- A laboratory estimate of the amount of
attenuation achievable by 98 of users when
properly fit - A population-based rating ? some users will get
more attenuation, some will get less
The NRR is only a population estimate, not a
predictor of individual attenuation.
17Noise Reduction Rating Determining an NRR
- 10 human subjects tested in a reverberant room
- Tested with ears open/occluded at nine
frequencies - Each subject tested 3x
- NRR calculated to be population average
A test subject in the Howard Leight Acoustical
Lab, San Diego, CA, accredited by the National
Voluntary Laboratory Accreditation Program (NVLAP)
18NRR
Noise Reduction Rating Determining an NRR
NRR
5
4
Number of test subjects
3
2
1
28
30
32
26
22
24
14
18
20
19
23
25
27
Attenuation
19Noise Reduction Rating
Real-World Attenuation ? NRR
192 users of a flanged reusable earplug 27 NRR
50
NRR 27 Multiple-Use Earplug
40
Retraining and refitting resulted in an average
14 dB improvement for this group
30
Attenuation in dB
20
10
0
-10
From Kevin Michael, PhD and Cindy Bloyer Hearing
Protector Attenuation Measurement on the End-User
20Noise Reduction Rating
NIOSH Earmuffs NRR 25 Formable Earplugs NRR
50 All Other Earplugs NRR 70
OSHA NRR 2 (feasibility of engineering
controls)
CSA Class A up to 100 B up to 95 C up to 90
Fit Test
21Noise Reduction Rating
- The EPA recently made an announcement about a
proposed change to the Noise Reduction Rating
NRR - This is the first change in hearing protector
regulation in nearly 30 years
22Noise Reduction Rating
Determining New NRR
- 20 human subjects tested in a simulated
industrial room - Subject trained then fits their own earplugs
- Tested with ears open / occluded at 9 frequencies
- Each subject tested 2x
- NRR calculated to be population average
23New NRR (NRsa)
5
4
Number of test subjects
3
2
1
22
24
11
14
18
20
30
28
26
33
19
23
25
27
Attenuation
24Noise Reduction Rating
20th Proficient Users
80th Minimally-trained
Current NRR Label Mock-up of New Label
25Noise Reduction Rating
- How to Apply the New Label
Two-number range displays the estimated
protection achievable by minimally-trained users
80 versus proficient users 20.
A wider range indicates greater variability in
the fit of that HPD. Smaller ranges indicate more
consistency of fit. For example, earmuffs will
usually have a tighter fitting range than
earplugs, and may have a smaller NRR range.
80
20
26Noise Reduction Rating
Factors in Achieving the NRR
1.FIT
2. WEAR TIME
30 dB
A worker who selects an earplug with an NRR of 30
but then removes that HPD for just
effectively reduced his 8-hour NRR to just
22 dB
18 dB
26 dB
24 dB
In noise exposures, small intervals of no
protection quickly void large intervals of
adequate protection.
27Noise Reduction Rating
Although the new labeling regulation takes effect
whenever the final rule is published by the EPA,
there are a number of actions you can take now to
prepare your Hearing Conservation Program for the
change.
- Evaluate Noise Spectra
to determine if
spectral balance corrections will be necessary - Update HC Training Program
on proper fit of hearing protectors.
Hold a Toolbox Training and hold a refresher
fit training session.
28Noise Reduction Rating
- Evaluate Current HPD Selection to determine
whether they are appropriate for your noise
environment. Use the Howard Leight Hearing
Protector Selector for recommendations. - Upgrade to One-on-One Training research studies
confirm that one-on-one training is superior to
group training
29Noise Reduction Rating
Provides an accurate, real-world picture of your
employees hearing protector effectiveness.
- Identify if your employees are
- Receiving optimal protection
- Require additional training
- Need to try a different earplug style
30Noise Reduction Rating
- As a problem solver
- Derating Schemes
- One-on-One Training
- HPD Selection
- NRR Change
31Noise Reduction Rating
- As a Problem Solver
- Continuously monitors in noise level at the
workers ear - The only true measure of the hazard!
32Reducing Costs of Hearing Loss
33Reducing Costs of Hearing Loss
Sample HL Compensation
Jurisdiction One Ear (Max) Both Ears (Max) Comments
NC 37.2k 80k aids
SC 38.7 (80 wks) 80k (165 wks) NMER
TN 38.6k 77.2k aids
DOL -LSA 52 wks 200 wks aids
NMER No minimum exposure required
Source AIHA Noise Manual
34Reducing Costs of Hearing Loss
- Indicators for Hearing Loss
- Standard Threshold Shift
- Temporary Threshold Shift
- Recordable Hearing Loss
- Dosimetry
- In-ear Dosimetry
- Personal Attenuation Level (PAR)
- Hearing Loss Compensation
35Reducing Costs of Hearing Loss
Lagging Indicators vs. Leading Indicators
36Reducing Costs of Hearing Loss
- Indicators for Hearing Loss
- Standard Threshold Shift
- Temporary Threshold Shift
- Recordable Hearing Loss
- Dosimetry
- In-ear Dosimetry
- Personal Attenuation Level (PAR)
- Hearing Loss Compensation
37Reducing Costs of Hearing Loss
Fit Testing
In-Ear Dosimetry
38- In-ear dosimetry measures/records workers actual
noise dose, with and without protection - Provides real-time monitoring and alerts when
worker approaches/exceeds safe limits - Only metric with direct potential to measure and
prevent further progression of occupational
hearing loss
39Reducing Costs of Hearing Loss
40Research gt Alcoa Intalco Works
Reducing Costs of Hearing Loss
- Mean Hearing Threshold (2k, 3k, 4kHz) 2000
2007 (N 46) - Employees using continuous in-ear dosimetry
starting in 2005
41Preventive Action After NIHL
Reducing Costs of Hearing Loss
In practice, an OSHA-recordable STS is not a
preventive action It is documentation of a
hearing loss after the fact. How soon will an
employee suffering NIHL be re-fit / re-trained ?
Best case scenario per Hearing
Conservation Amendment
In-ear dosimetry worst case scenario
1 Day
42In-ear dosimetry as a Problem Solver
Reducing Costs of Hearing Loss
In-ear monitoring as a Problem Solver
- Employees with Documented Noise-Induced Hearing
Loss or Standard Threshold Shift STS - Employees At-Risk for NIHL
- Employee Training Sampling
- Dual-Protection/Extreme Noise Exposure
- Engineering Controls
43Reducing Costs of Hearing Loss
Real-Ear Attenuation at Threshold (R.E.A.T.)
Loudness Balance (Real-Ear Attenuation Above
Threshold)
Microphone in Real-Ear (M.I.R.E.)
In-Ear Dosimetry
44Ear plug fit-testing methods
Audiometric FitCheck EARfit VeriPRO
REAT REAT MIRE REAAT
Sound booth Very Quiet Room Quiet Room Anywhere
PAR PAR Derived PAR PAR
Any earplug Any earplug Selected modified earplugs Any earplug
Special training required Special training required Special training required Anyone can perform
45Reducing Costs of Hearing Loss
OSHA Alliance Best Practice Bulletin www.hearing
conservation.org
Additional Information www.howardleight.com
46Pre and Post-Test
Fit-Testing as a Training Tool
- How well can users predict their attenuation
after a short fit-testing training session?"
47Pre and Post-Test
Fit-Testing as a Training Tool
- Ability to Predict Noise Reduction
56
32
12
48Reducing Costs of Hearing Loss
Published NRR
49Reducing Costs of Hearing Loss
Personal Factors Gender Age Years
in Noise Ear Canal Size Familiarity
Model of Earplug Program Factors Group
Trainings Personal Trainings
50REDUCING COSTS / CLAIMS
Reducing Costs of Hearing Loss
Published NRR
Trying a second earplug often improves attenuation
51Earplug fit-testing as a Problem Solver
Reducing Costs of Hearing Loss
- Training tool for noise-exposed workers
- Train-the-trainer tool
- Follow-up on significant threshold shifts in
hearing - Documentation of HPD adequacy
- Assessment of overall HCP effectiveness
- Match HPD to workers specific noise level
- Selection of appropriate HPDs for new hires
- Benefits per Best Practices Bulletin (OSHA
Alliance)
52Reducing Costs of Hearing Loss
Tools for HCP Prevention Metrics
- PROS
- Estimate Measure
- NRR obsolete
- Fulfills OSHA compliance
- Eliminates need for de-ratings
- Medico-legal cases
- Delineates non-occupational
- Eliminates double protection
- Provides employee feedback
- (HPD Inventory control)
- CONS
- Cost
- Time Investment
- Not standardized
53Training Motivation
54Training Motivation
Common Objections to Wearing HPDs
I already lost some of my hearing, so why should
I wear them?
Wont I get an ear infection?
Hearing protectors are uncomfortable to wear.
I dont need them! I am used to the noise.
I cant hear my co-workers if I wear them.
I can always get fit with a hearing aid.
Can I hurt my eardrums if I insert an earplug to
deeply.
My machine sounds different.
55Training Motivation
Personalize Hearing Loss
- Show, Dont Tell
- Provide copy of annual audiogram to worker
- Use personal examples to demonstrate consequences
of hearing loss - Ask questions
- What is your favorite sound?
- What sound would you miss
the most if you couldnt hear? - What sounds connect you to
people and your environment?
56Training Motivation
Demonstrate Future Risk
- Training Materials
- www.hearforever.org
- www.hearingconservation.org
- atl.grc.nasa.gov/HearingConservation/Resources/ind
ex.html - www.cdc.gov/niosh/topics/noise
- www.dangerousdecibels.org
www.hearforever.org/ILCA2010
57Training Motivation
- Send Clear Message On Off Job
- HC Part of Everyday Life
- Include recreational hearing conservation in
annual training - Provide extra HPDs for home use
- Promote Hearing Conservation at company/family
events
58Training Motivation
Remove Barriers to HPD Use
- Make HPDs Available
- Highlight where to find HPDs in annual training
- Make sure HPDs are well-stocked and accessible
- Include group of workers in selection process for
increased acceptance - Offer wide variety to match comfort, job
requirements
59- Listen Up!
- Hear Forever
- Make Hearing Conservation a Part of Your Everyday
Life
HearForever.org