Noise-Induced Hearing Loss - American Academy of Audiology

Assessing Hearing Protectors in the
Clinic- How to Perform CPT 92596
Assessing Hearing Protectors
in the Clinic:
How to Perform CPT Code 92596
Tom Thunder, AuD, FAAA, INCE Bd. Cert.
Audiologist and Acoustical Specialist
Northern Illinois University, DeKalb, IL
Acoustic Associates, Palatine, Illinois
Interacts with …
• Smoking
• Paint solvents (toluene)
• Carbon monoxide (CO)
• Strenuous exercise
State of Washington
Workers’ Compensation
Claims for Hearing Loss
• Increased nearly 12-fold during 1984-1998.
• 90% of the claimants received permanent
partial disability compensation.
• Identifiable costs exceeded $57 million
dollars in 1998.
“…occupational hearing loss is probably much more
common than usually recognized, and contemporary workers
may still face substantial risk for hearing loss.”
Based on 27,019 claims filed
Acoustic Associates, Ltd.
Tom Thunder, AuD, INCE ( tthunder@comcast.net)
Daniell et al. Am J Ind Med.
2002 Dec;42(6):502-10.
Excess Risk in %
American Academy of
Audiology (April 2009)
Noise-Induced Hearing Loss
50
40
30
20
10
0
1
8
“… is insidious, permanent, and irreparable … and partially the cause
in more than 1/3 of those who have hearing loss.
“… is the most prevalent, irreversible industrial disease and, in a
developed country, the biggest compensable occupational hazard.”
25
80 85 90
Average Daily Noise Level in dBA
World Health Organization, 1997. www.who.ing
OSHA Noise Standard
(1971, 1983)
Use feasible administrative or
1 engineering controls to reduce
noise exposure below 90 dBA
If exposure can’t be reduced, use
2 adequate hearing protection.
Administer a continuing,
3
effective hearing conservation
program (HCP) above 85 dBA.
The most significant number of workers
seeing an audiologist for NIHL were 40-45
years old. They would have entered industry
around 1972-1977 when OSHA was strong.
43% of the companies where these baby
boomers worked had no hearing
conservation program.
Source:, 1997 Annual
Report on Occupational
Hearing Loss, Michigan.

Assessing Hearing Protectors in the
Clinic- How to Perform CPT 92596
Bureau of Labor and Statistics
Occupational Injuries for 2007
Hearing loss was the 2 nd highest specific reported
illness in all of the last four years since OSHA has
required separate reporting of hearing loss.
Hearing Protection Devices
workplace noise effective employee exposure
A-Weighted Sound Level (dBA)
125
115
105
95
85
dBC - NRR = dBA
C – A Differences
Mean C-A = 2 dB
-2 0 2 4 6 8 10 12 14
C - A Value (dB)
Combined Industrial Noises
Special Noises (see text)
C-A > 7 dB = 4%
Linear Curve
Tom Thunder, AuD, INCE ( tthunder@comcast.net)
Relative Sound Pressure Level in dB
Over Reliance on Hearing
Protection Devices
With OSHA’s lax
enforcement policy
of the 80s,
management of the
90s and beyond
have relied on
protection to the
extent that if HPDs
were issued, the
noise problem
vanished.
20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
16
Weighting Scales
31.5
63
125
250
American Academy of
Audiology (April 2009)
500
1000
Frequency in Hz
2000
4000
8000
C-weighting
A-weighting
Questionable Perception of
HPD Performance
Most HR
officers and
safety
managers
believe that
the higher the
NRR, better
the
protection.
NRR (dB)
30
25
20
15
10
5
0
Labeled vs. Field Values
Down
Custom
Laboratory
Field
16000
Sound-Ban 10/20
UltraFit
V-51R
POP/Soft
EP-100
Misc. 3-flange
Classic
Peltor H9A
Misc. M uffs
M SA Mk IV
Hlbrg. No-Noise
Bilsom 2313
Peltor H7P3e
Bilsom UF-1

Assessing Hearing Protectors in the
Clinic- How to Perform CPT 92596
NRR (dB)
Real-Ear Attenuation (dB)
Using the NRR
Not Really Right
dBA P =dBA w – ½ (NRR – 7)
workplace noise
protected employee exposure
• 50% derating: a safety margin to account for the field vs.
lab difference in the labeled NRR.
• 7-dB correction: another safety margin to account for the
spectral uncertainty (i.e., the difference between the C
and A weighted levels).
35
30
25
20
15
10
5
0
-10
0
10
20
30
40
Predicted vs. Field Values
V-51R
EP-100
Field
Soft
Custom
Method B
SoundBan
Com-Fit
UltraFit
Mark IV
H7P3E
Classic
H9A
UF-1
Classic+UF-1
Attenuation Data
Tom Thunder, AuD, INCE ( tthunder@comcast.net)
Label Test
50
.125 .250 .500 1.0 2.0 4.0 8.0
Frequency (kHz)
0
15 Std. Dev.
ANSI S12.6 -1997 (R2002)
REAT
(Real-Ear at Threshold)
ANSI S12.6 – 1997
(R2002)
Sound-field thresholds
measured without HPD
Sound-field thresholds
measured with HPD
The difference is the
attenuation of the HPD
(insertion loss)
American Academy of
Audiology (April 2009)
Method A:
- Fit by tester
- 10 experienced subjects
- 3 trials (30 runs)
Method B:
- Fit by subject
- 20 naïve subjects
- 2 trials (40 runs)
Laboratory Testing of HPDs
Reverberant Room
1/3
1/3-Octaveband Noise Signal
Best Practice Bulletin:
Hearing Protection-Emerging Trends: Individual Fit Testing
Any population-based statistical estimate of hearing
protector performance is a poor estimate of individual
performance.
If the purpose of HPD evaluation is to determine how well
specific HPDs work on specific people, then they must be
tested on individual people (similar to the quantitative fit
testing of respirators).
http://www.hearingconservation.org/docs/AllianceRecommendationForFitTesting_Final.pdf

Assessing Hearing Protectors in the
Clinic- How to Perform CPT 92596
Ear Protector Attenuation Measurement
An assessment of ear protector performance for a specific ear
protector on a specific individual. Why do it?
Fit verification – to verify “adequacy” of fit
STS evaluations – to assess poor fit as a potential
contribution to the change in hearing
Work-related evaluation – to factor in HPD use
Training and education – an OSHA required
component of an effective HCP
HPD selection – and aid in selecting a good HPD for new
employees
Documentation – establishes evidence that HPDs were
selected and fit for legal records
EARfit ® Technology
Dual element
microphone
Simultaneous
measurement inside
and outside HPD yields
noise reduction (NR)
Specially prepared
protector called a
“probed HPD”
Advantages
F-Mire Approach
Quick – 8 seconds per ear
Objective (non-linear HPDs)
Can test one or both ears
Quiet is not needed
Hearing loss not an issue
Great documentation
Tests at 125 and 8000 Hz
Disadvantages
Tom Thunder, AuD, INCE ( tthunder@comcast.net)
Cost
Space
Can only test
manufacturer’s HPDs
Special probed HPDs
Acoustic flanking at high
frequencies
For a short movie clip, see: http://www.e-a-rfit.com/process.aspx
American Academy of
Audiology (April 2009)
F-MIRE (Field Microphone in Real-Ear)
Utilizes the same real-ear approach to
verifying the insertion gain of hearing
aids, except here you are measuring the
insertion loss of earplugs.
Individual HPD Fit Test:
EARfit ® Technology
Software provides the stimulus, calculations, and
ear-canal-to-sound-field transfer function.
Loudness Balance
The VeriPRO uses a 3-part
loudness balance process to
measure the attenuation of a
patient’s earplug fit in each ear
over a range of 5 frequencies.
With this real-world data, you
can find out whether your
patient is receiving optimal
protection, requires additional
training on how to fit their
earplugs, or if they need to try a
different model.

Assessing Hearing Protectors in the
Clinic- How to Perform CPT 92596
Developed in conjunction
with the House Ear
Institute and uses
sophisticated software in a
user-friendly format to
determine the Personal
Attenuation Rating (PAR)
your patient receives.
The VeriPRO package
consists of PC-based
software, an audio
processor, a USB cable,
and an audiometrically
optimized headset.
Renee Besette of Howard Leight
by Sperian takes a visitor
through this simple audio
demonstration
http://www.ohscanada.com/ohstv/Howard-Leight-NSC-2007.asp
Five frequencies are balanced (250, 500, 1k, 2k and 4k Hz)
Using the mouse, raise or lower
the slider bar until the volume
in your left ear matches the
volume in your right ear (which
always stays the same).
Compare the volume only, not
the quality or pitch of the tone.
When you have reached a
balance, click MATCH to move
on to the next frequency.
First, a balance is done to get an unprotected reference level for the left ear.
Second, a plug is inserted in the right ear and a balance is done to determine the
PAR for the right plug.
Third, a plug is inserted in the left ear and a balance is done to determine the PAR
for the left plug (measures the change in level on the left).
A color visual is given to show how well a specific
protector works for that patient.
Tom Thunder, AuD, INCE ( tthunder@comcast.net)
American Academy of
Audiology (April 2009)
In this approach, users match the volume of a tone in one ear to the other ear.
Informational graphics and instructional text guide the user through the process.
At the end of a Check, users view a report giving the patient’s PAR
for the HPD worn. The report can be printed or saved as a PDF.
Loudness Balance Approach
Advantages
Professional efficiency
Works with any earplug
Tests both ears
Good documentation
Quiet not needed
Disadvantages
Cost - $2,900
Space
Won’t work with muffs or caps
Subjective
Hearing loss can be an issue
Relatively slow – 9 min

Assessing Hearing Protectors in the
Clinic- How to Perform CPT 92596
REAT (Real-Ear at Threshold)
Based on ANSI S12.6 (a lab standard).
Audiometric
Room
Warbled Pure Tone Signal
Advantages
Tom Thunder, AuD, INCE ( tthunder@comcast.net)
Sound-Field
thresholds are
measured without the
HPD
Sound-Field
thresholds are then
measured with HPD
The difference is the
attenuation of the
HPD (insertion loss)
PAR Patient ©- a Microsoft Excel ® Template
American Academy of
Audiology (April 2009)
Why don’t audiologists measure HPD performance?
Most audiologists have the capability to measure attenuation …
they just don’t know how to calculate the individual NRR (called
the Personal Attenuation Rating).
Originally developed to give students a lab exercise.
Automatically calculates the patient’s PAR
Active Link to Look up the HPD’s laboratory NRR (NIOSH)
Active Link to Look up noise levels (AEARO database)
Estimates the effective (protected) noise level
Generates a range of protected noise levels based on the
probable frequency spectrum of the patient’ s exposure
Available from: Acoustic Associates (info@AcousticAssociates.com)
Printed Document (Upper Half) Printed Document (Lower Half)
REAT Approach
A common clinical test
Follows the REAT method
of the ANSI standard
Negligible cost
Works with any HPD
Disadvantages
Relatively slow – 8 min
Subjective
Binaural measure
Hearing loss can be an
issue
No one needs to lose
his or her hearing in
order to earn a living.
Noise-induced hearing
loss is preventable.
Noise-induced hearing loss
remains one of the most
prevalent occupational
conditions and is found in a
wide range of industries.