Transcript Best Practices in Hearing Conservation

Hearing
Conservation
Theresa Y. Schulz, PhD.
Lt. Col. USAF (ret.)
Topics
Noise And Acoustics
Noise Reduction
Reducing Costs for Hearing Loss
Motivating Workers
Noise + 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
Is Permanent + 100% Preventable
Noise + Acoustics
Noise-induced hearing loss is the
most common permanent and
preventable occupational injury
in the world.
World Health Organization
Noise + Acoustics
Worker’s Compensation
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)
Noise + Acoustics
United States Statistics
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)
Noise + Acoustics
Non-Occupational
Occupational
Noise + Acoustics
Noise Measurement Devices
SOUND LEVEL
METER
PERSONAL
DOSIMETER
IN-EAR
DOSIMETER
Sound is measured
immediately in a
specific area
Sound “averaged”
throughout day for
sample employee/job
Collects personal noise
dose – the only real
measure of risk
NOISE+AND
Noise
Acoustics
ACOUSTICS
- Hierarchy
~ Hierarchy
of Controls
of Controls
ENGINEERING
CONTROLS
• Buy Quiet
• Vibration Pads
• Enclosures
ADMINISTRATIVE
CONTROLS
• Rotate Workers
• Barriers
• Extended
Breaks
• Isolation
•2nd/3rd Shift
PERSONAL
PROTECTIVE
EQUIPMENT
NOISE+AND
Noise
Acoustics
ACOUSTICS ~ Hierarchy of Controls
Ototoxic Chemicals
•
•
•
•
Ototoxic by themselves
Synergistic effect with noise
Large differences in sensitivity
Recommend: increased frequency
of audiometric testing
Confirmed Ototoxics
Ethyl Benzene
Lead and inorganic
compounds (as Pb)
Styrene
Toluene
Trichloroethylene
Synergistic Ototoxics
NOISE
• Carbon Monoxide
Possible
Carbon disulfide
• Hydrogen Cyanide
n-Hexane
Xylene
Noise
Reduction
Rating
(NRR)
Hearing Protection Selection
Hearing Protection Selection Factors
Comfort
Noise Reduction
Size
Communication
Job Requirements
Hygiene
Use with Other PPE
• Proper
Select
The
Selecting
Every
Keep
Consider
right
workers
ear
HPDs
care
hearing
job
HPDs
canal
and
thathas
with
can
protector
suitable
its
connected
requirements
maintenance
work
own
with
shape
attenuation
should
other
to their
can
in
and
PPE
HPD
feel
comfortable
for
size
environment
selection
extend
without
noise
life
compromise
environment
and
ofmay
• performance
One protector
Avoid
Ensure
Uniform
Detectable
Cap-mounted
overprotection
proper
attenuation
earplugs
fitHPDs
with
• earmuffs
notmarginal
in
variety
allows
for
Examine
process
satisfy
speech/signals
of for
and
earplug
all
noise
industries
hard
workers
clean
environments
sizes
to
all
be
multiple-use
hear
and
shapes
more
• hats
Offer
Hi-visibility
a
variety
earmuffs
of
naturally
daily
• earplugs
earplugs
Consider
Sized
for
Multiple-position
dark/high
multiple-use
or
banded
earmuffs
traffic
• earmuffs
to meetand
earplugs
Sound
areas
Clean
amplification
varying
forreplace
full-brim
worker
intermittent
earmuffs
ear
cushions
hats
needs
for
noise
workers
on
and
or
• hard
Low-pressure
Dielectric
HPDs
foam
for
preferences
electronic
with
hearing
every
earmuffs
4-6 for
• earmuffs
earplugs
electrical
Ultraslim
for
neckband
smaller
impact
impairment
months
noise.
ear canals
environments
earmuffs
with welding
shields
Noise 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)
0 dB
0 dB
33 dB
EAR #1
EAR #2
EAR #3
How much protection?
Fitting Tips
Good Fit vs Bad Fit
90
Attenuation in dB
80
70
60
50
40
30
20
10
0
-10
Max Good Fit
NRR = 33dB
Max Poor Fit
NRR = 0dB
8000
6300
4000
3150
2000
1000
500
250
125
Frequency in Hz
Noise Reduction Rating
Noise 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.
Noise 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)
Noise Reduction Rating – Determining an NRR
NRR
NRR
Number of test subjects
5
4
3
2
1
14
18 20 22 24 26 28 30 32
19
23 25 27
Attenuation
Noise Reduction Rating
Attenuation in dB
Real-World Attenuation
≠ NRR
192 users of a flanged reusable earplug ~ 27 NRR
50
NRR = 27 Multiple-Use Earplug
40
30
20
10
0
-10
From Kevin Michael, PhD and Cindy Bloyer “Hearing Protector Attenuation Measurement on the End-User”
Retraining
and refitting
resulted in an
average
14 dB
improvement
for this group
Noise Reduction Rating
De-Rating Methods
OSHA
NIOSH
CSA
NRR ÷ 2
Earmuffs
NRR – 25%
Class
A up to 100
Formable Earplugs
NRR – 50%
B up to 95
(feasibility of
engineering
controls)
Fit
Test
All Other Earplugs
NRR – 70%
C up to 90
Noise Reduction Rating
Noise 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
Noise 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
New NRR (NRsa)
80% achieved > 20 dB
20% achieved > 26 dB
Number of test subjects
5
4
3
2
1
11
14
18 20 22 24 26 28 30
19
23 25 27
Attenuation
33
Noise Reduction Rating
Current NRR Label
80th %
20th %
Minimallytrained
Proficient
Users
Mock-up of New Label
Noise 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%].
80%
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.
Noise Reduction Rating
Factors in Achieving the NRR
1.FIT
2. WEAR TIME
30
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 …
dB
5 min
10 min
15 min
30 min
26 dB
24 dB
22 dB
18 dB
In noise exposures, small intervals of no protection
quickly void large intervals of adequate protection.
Noise Reduction Rating
What Can I Do Now?
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.
Noise Reduction Rating
What Can I Do Now?
• 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
Noise Reduction Rating
Earplug Fit Testing
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
Noise Reduction Rating
Earplug Fit Testing
As a problem solver:
• Derating Schemes
• One-on-One Training
• HPD Selection
• NRR Change
Noise Reduction Rating
In-Ear Dosimetry
As a Problem Solver
• Continuously monitors
in noise level at the
workers ear
• The only true measure
of the hazard!
Reducing Costs of
Hearing Loss
Reducing Costs of Hearing Loss
Sample HL Compensation*
One Ear
(Max)
$37.2k
$38.7
Both Ears Comments
(Max)
(80 wks)
(165 wks)
TN
$38.6k
$77.2k
+ aids
DOL -LSA
52 wks
200 wks
+ aids
Jurisdiction
NC
SC
$80k
$80k
+ aids
*NMER
*NMER= No minimum exposure required
*Source: AIHA Noise Manual
Reducing 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
Reducing Costs of Hearing Loss
Lagging Indicators vs. Leading Indicators
Reducing 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
Reducing Costs of Hearing Loss
Fit Testing
In-Ear Dosimetry
In-ear dosimetry measures/records
worker’s 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
Reducing Costs of Hearing Loss
Research
> Alcoa
Works
Reducing Costs
ofIntalco
Hearing
Loss
Mean hearing
threshold
and 4 kHz)2000 – 2007 (N = 46)
• Mean Hearing Threshold
(2k,
3k, (2,3,
4kHz):
Employees using continuous ESP starting in 2005
• Employees using continuous in-ear dosimetry starting in 2005
2000 - 2007 (N=46)
50
ESP Introduced
Mean HTL 3,4,6kHz
45
trend line
40
35
30
25
20
15
10
5
0
2000
2001
2002
2003
2004
Year of test
2005
2006
2007
Reducing Costs of Hearing Loss
Preventive Action After NIHL
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
• Retest
• Audiometric test
0
2
4
6
8
10
Months
12
14
• Notification
16
In-ear dosimetry
Reducing
Costs of
asHearing
a Problem
Loss
Solver
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
Reducing Costs of Hearing Loss
Real-Ear
Attenuation at
Threshold
Loudness Balance
(R.E.A.T.)
(Real-Ear Attenuation Above
Threshold)
Microphone
in Real-Ear
In-Ear Dosimetry
(M.I.R.E.)
Ear 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
Selected
modified
earplugs
Any earplug
Any earplug
Special training Special training Special training
required
required
required
Anyone can
perform
Reducing Costs of Hearing Loss
OSHA Alliance: Best Practice Bulletin
www.hearingconservation.org
Additional Information
www.howardleight.com
Fit-Testing
as a Training Tool
Pre and Post-Test
“How well can users predict their
attenuation after a short fit-testing
training session?"
Fit-Testing
as a Training Tool
Pre and Post-Test
Ability to Predict Noise Reduction
(Each subject estimated atten. for each ear)
Number of Ears
20
18
56%
16
14
12
10
32%
8
6
4
12%
2
0
Within 5 dB
category
+/- 7.5 dB
+/- 12.5 dB
(one Category off) (2 categories off)
Reducing Costs of Hearing Loss
Variation from Published NRR
10
Published
NRR
0
-5
-10
-15
-20
Distribution of PARs
-25
12
-30
0
10
20
30
40
50
10 60
Workers
Workers
Difference in dB
5
70
80
90
100
8
6
4
2
0
-30
-25
-20
-15
-10
-5
0
5
10
Variation from Published NRR
15
20
25
30
Reducing Costs of Hearing Loss
Personal Factors
Gender
Age
Distribution of PARs
12
Years in Noise
Workers
10
Ear Canal Size
8
6
Familiarity
4
Model of Earplug
2
0
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
Program Factors
Variation from Published NRR
# Group Trainings
# Personal Trainings
REDUCING
Reducing
Costs
COSTS
of Hearing
/ CLAIMSLoss
Difference on 2nd / 3rd Test
10
Variation from NRR
5
Published
NRR
0
-5
-10
-15
-20
-25
-30
Subjects
Trying a second earplug often
improves attenuation
Reducing Costs of Hearing Loss
Earplug fit-testing as a Problem Solver
• 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 worker’s specific noise level
• Selection of appropriate HPDs for new hires
•
Benefits per Best Practices Bulletin (OSHA Alliance)
Reducing Costs of Hearing Loss
Tools for HCP Prevention Metrics
PROS
• Estimate
CONS
Measure
• Cost
• NRR obsolete
• Time Investment
• Fulfills OSHA compliance
• Not standardized
• Eliminates need for de-ratings
• Medico-legal cases
• Delineates non-occupational
• Eliminates double protection
• Provides employee feedback
• (HPD Inventory control)
Training +
Motivation
Training + Motivation
Common Objections to Wearing HPDs
“I already lost some of my hearing, “Won’t I get an ear
so why should I wear them?”
infection?”
“Hearing protectors “I don’t need them!
are uncomfortable I am used to the
to wear.”
noise.”
“I can’t hear my
co-workers if I
wear them.”
“Can I hurt my eardrums if I insert an
earplug to deeply.”
“I can always
get fit with a
hearing aid.”
“My machine sounds different.”
Training + Motivation
Personalize Hearing Loss
Show, Don’t 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 couldn’t hear?
• What sounds connect you to
people and your environment?
Training + Motivation
Demonstrate Future Risk
Training Materials
• www.hearforever.org
• www.hearingconservation.org
• atl.grc.nasa.gov/HearingConserv
ation/Resources/index.html
• www.cdc.gov/niosh/topics/noise
• www.dangerousdecibels.org
www.hearforever.org/ILCA2010
Training + 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
Training + Motivation
Remove Barriers to HPD Use
Make HPDs Available
• Highlight “where to find
HPDs” in annual training
• Make sure HPDs are wellstocked and accessible
• Include group of workers in
selection process for
increased acceptance
• Offer wide variety to match
comfort, job requirements
Listen Up!
Hear Forever
Make Hearing
Conservation a Part
of Your Everyday Life
HearForever.org