Hearing conservation theresa y schulz phd lt col usaf ret
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Hearing Conservation Theresa Y. Schulz, PhD. Lt. Col. USAF (ret.). Topics. Noise And Acoustics. Motivating Workers. Noise Reduction. Reducing Costs for Hearing Loss. Noise + Acoustics. Is Permanent + 100% Preventable. Noise-Induced Hearing Loss Causes no pain Causes no visible trauma

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Hearing Conservation Theresa Y. Schulz, PhD. Lt. Col. USAF (ret.)

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Hearing conservation theresa y schulz phd lt col usaf ret

Hearing ConservationTheresa Y. Schulz, PhD.Lt. Col. USAF (ret.)


Topics

Topics

Noise And Acoustics

Motivating Workers

Noise Reduction

Reducing Costs for Hearing Loss


Noise acoustics

Noise + Acoustics

Is Permanent + 100% Preventable

  • 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


Noise acoustics1

Noise + Acoustics

Noise-induced hearing loss is the most common permanent and preventable occupational injury in the world.

World Health Organization


Noise acoustics2

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 acoustics3

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 acoustics4

Noise + Acoustics

Non-Occupational

Occupational


Noise acoustics5

Noise + 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


Noise and acoustics hierarchy of controls

NOISE AND ACOUSTICS ~ Hierarchy of Controls

Noise + Acoustics - Hierarchy of Controls

  • ADMINISTRATIVE CONTROLS

  • Rotate Workers

  • Extended Breaks

  • 2nd/3rd Shift

PERSONAL PROTECTIVE EQUIPMENT

  • ENGINEERING CONTROLS

  • Buy Quiet

  • Vibration Pads

  • Enclosures

  • Barriers

  • Isolation


Hearing conservation theresa y schulz phd lt col usaf ret

NOISE AND ACOUSTICS ~ Hierarchy of Controls

Noise + Acoustics

Confirmed Ototoxics

Ethyl Benzene

Lead and inorganic compounds (as Pb)

Styrene

Toluene

Trichloroethylene

PossibleCarbon disulfide

n-Hexane

Xylene

  • Synergistic Ototoxics

    • Carbon Monoxide

    • Hydrogen Cyanide

NOISE

  • Ototoxic Chemicals

  • Ototoxic by themselves

  • Synergistic effect with noise

  • Large differences in sensitivity

  • Recommend: increased frequency of audiometric testing


How we hear

How We Hear


How we hear1

How We Hear

  • The Auditory System

Chem/Elec

Acoustical

Hydraulic

Mechanical


How we hear2

How We Hear

  • High Frequency Sounds of Speech

CH

S

TH

P

T

F

SH

K

H


Noise reduction rating nrr

Noise Reduction Rating(NRR)


Noise reduction rating

Noise Reduction Rating

  • How much noise is reaching the ear of the worker ?

Noise Level =100 dB

Noise Reduction Rating =30 dB

That is completely unknown …

(55 – 104 dB)


Noise reduction rating1

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

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)


Hearing conservation theresa y schulz phd lt col usaf ret

NRR

Noise Reduction Rating – Determining an NRR

NRR

5

4

Number of test subjects

3

2

1

26

28

30

32

24

22

14

18

20

19

23

25

27

Attenuation


Hearing conservation theresa y schulz phd lt col usaf ret

Real user attenuation <0 to 38 dB

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”


Noise reduction rating2

Noise Reduction Rating

  • De-Rating Methods

OSHA

NRR ÷ 2

(feasibility of engineering controls)

NIOSH

Earmuffs

NRR – 25%

Formable Earplugs

NRR – 50%

All Other Earplugs

NRR – 70%

CSA

Class

A up to 100

B up to 95

C up to 90

Fit Test


Noise reduction rating3

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 rating4

Noise Reduction Rating

  • Three New Labels


Noise reduction rating5

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 nr sa

New NRR (NRsa)

80% achieved > 20 dB

20% achieved > 26 dB

5

4

Number of test subjects

3

2

1

24

22

11

14

18

20

26

28

30

33

19

23

25

27

Attenuation


Noise reduction rating6

Noise Reduction Rating

20th %

Proficient Users

80th %

Minimally-trained

Current NRR Label Mock-up of New Label


Noise reduction rating7

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%].

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%


Noise reduction rating8

Noise Reduction Rating

30 min

5 min

10 min

15 min

Factors in Achieving the NRR

1.FIT

2. WEAR TIME

30dB

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.


Noise reduction rating9

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 rating10

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 rating11

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 rating12

Noise Reduction Rating

  • Earplug Fit Testing

  • As a problem solver:

  • Derating Schemes

  • One-on-One Training

  • HPD Selection

  • NRR Change


Noise reduction rating13

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


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

Sample HL Compensation*

*NMER= No minimum exposure required

*Source: AIHA Noise Manual


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

Sample HL Compensation*

*NMER= No minimum exposure required

*Source: AIHA Noise Manual


Hearing conservation theresa y schulz phd lt col usaf ret

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


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

Lagging Indicators vs. Leading Indicators


Hearing conservation theresa y schulz phd lt col usaf ret

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


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

In-Ear Dosimetry

Fit Testing


Hearing conservation theresa y schulz phd lt col usaf ret

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 occupationalhearing loss


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss


Research alcoa intalco works

Research > 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


Preventive action after nihl

Preventive Action After NIHL

Reducing Costs of Hearing Loss

• Audiometric test •Retest •Notification

0 246810121416

Months

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


In ear dosimetry as a problem solver

In-ear dosimetry as a Problem Solver

Reducing Costs of Hearing Loss

  • 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


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing 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


Ear plug fit testing methods

Ear plug fit-testing methods


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

OSHA Alliance: Best Practice Bulletin

www.hearingconservation.org

Additional Information

www.howardleight.com


Hearing conservation theresa y schulz phd lt col usaf ret

Field Verification – Fit-Testing

"Learned A LOT about best earplugs for me"

"I know how to better fit my earplugs now."

"Recently had threshold shift" "Found better earplugs"

"I had no idea I was not using my earplugs correctly."

"Very glad I did the fitting test. Now I know the correct way to fit my ear plugs.”

"I found a more comfortable fit. It was very beneficial."

"I was amazed with the results after being shown the proper way to use earplugs.

"Feel like am protected now!"


Hearing conservation theresa y schulz phd lt col usaf ret

Pre and Post-Test

Fit-Testing as a Training Tool

  • “How well can users predict their attenuation after a short fit-testing training session?"


Hearing conservation theresa y schulz phd lt col usaf ret

Pre and Post-Test

Fit-Testing as a Training Tool

  • “How much noise do you think your earplugs block?”

  • Self-Efficacy

  • 76% (13 of 17) judged attenuation as HIGHER post-test


Fit testing as a training tool

Fit-Testing as a Training Tool

  • Data show improved PARs!

  • Results

  • InitialRE=19 LE=22

  • Final RE=29 LE=27

  • Average improvement 7.5 dB


Hearing conservation theresa y schulz phd lt col usaf ret

Pre and Post-Test

Fit-Testing as a Training Tool

  • Are you better able to assess the effectiveness of your earplugs after VeriPRO fit-testing?

  • 12345

  • No MaybeNo change Improved Yes

  • Post-Test

64% (11 of 17) rated their abilityHIGHER post-test


Hearing conservation theresa y schulz phd lt col usaf ret

Fit-Testing as a Training Tool

Pre and Post-Test

Don't know

how

Expert

Not good

Not good

Expert

I do OK

I do OK

Pretty good

Pretty good

I do OK

Pretty good

Expert Fitter

Post-Test Ability

Initial Ability


Hearing conservation theresa y schulz phd lt col usaf ret

Pre and Post-Test

Fit-Testing as a Training Tool

20

18

16

14

12

Number of Ears

(Each subject estimated atten. for each ear)

10

8

6

4

2

0

Within 5 dB

category

+/- 7.5 dB

(one Category off)

+/- 12.5 dB

(2 categories off)

  • Ability to Predict Noise Reduction

56%

32%

12%


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

Published NRR


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

Personal Factors

Gender

Age

Years in Noise

Ear Canal Size

Familiarity

Model of Earplug

Program Factors

# Group Trainings

# Personal Trainings


Reducing costs claims

REDUCING COSTS / CLAIMS

Reducing Costs of Hearing Loss

Published NRR

Trying a second earplug often improves attenuation


Earplug fit testing as a problem solver

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)


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing 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


Hearing conservation theresa y schulz phd lt col usaf ret

Reducing Costs of Hearing Loss

Off-job+ On-job = STS

Off-job+ On-job = STS


Hearing conservation theresa y schulz phd lt col usaf ret

0 dB

0 dB

33 dB

EAR #1

EAR #2

EAR #3

How much protection?


Hearing conservation theresa y schulz phd lt col usaf ret

Frequency in Hz

1000

2000

3150

4000

6300

8000

250

500

125

90

Max Good Fit

NRR = 33dB

Max Poor Fit

NRR = 0dB

80

70

60

50

Attenuation in dB

40

30

20

10

0

-10

Good Fit vs Bad Fit


Training motivation

Training + Motivation


Training motivation1

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 motivation2

Training + Motivation

  • Demonstrate Future Risk

  • Training Materials

  • www.hearforever.org

  • www.hearingconservation.org

  • atl.grc.nasa.gov/HearingConservation/Resources/index.html

  • www.cdc.gov/niosh/topics/noise

  • www.dangerousdecibels.org

www.hearforever.org/vpppaivconference2010


Training motivation3

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 motivation4

Training + 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


Training motivation5

Training + Motivation

  • Hearing Loss Due To

  • Noise Exposure Is …

  • Painless

  • Permanent

  • Progressive

… and veryPreventable!


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