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

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

2. Topics Noise And Acoustics Motivating Workers Noise Reduction Reducing Costs for Hearing Loss

3. 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

4. Noise + Acoustics Noise-induced hearing loss is the most common permanent and preventable occupational injury in the world. World Health Organization

5. 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)

6. 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)

7. Noise + Acoustics Non-Occupational Occupational

8. 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

9. 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

10. 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

11. How We Hear

12. How We Hear • The Auditory System Chem/Elec Acoustical Hydraulic Mechanical

14. How We Hear • High Frequency Sounds of Speech CH S TH P T F SH K H

15. Noise Reduction Rating(NRR)

16. 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)

17. 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.

18. 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)

19. 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

20. 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”

21. 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

22. 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

23. Noise Reduction Rating • Three New Labels

24. 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

25. 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

26. Noise Reduction Rating 20th % Proficient Users 80th % Minimally-trained Current NRR Label Mock-up of New Label

27. 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%

28. 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.

29. 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.

30. 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

31. 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

32. Noise Reduction Rating • Earplug Fit Testing • As a problem solver: • Derating Schemes • One-on-One Training • HPD Selection • NRR Change

33. 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!

34. Reducing Costs of Hearing Loss

35. Reducing Costs of Hearing Loss Sample HL Compensation* *NMER= No minimum exposure required *Source: AIHA Noise Manual

36. Reducing Costs of Hearing Loss Sample HL Compensation* *NMER= No minimum exposure required *Source: AIHA Noise Manual

37. 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

38. Reducing Costs of Hearing Loss Lagging Indicators vs. Leading Indicators

39. 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

40. Reducing Costs of Hearing Loss In-Ear Dosimetry Fit Testing

41. 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

42. Reducing Costs of Hearing Loss

43. 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

44. Preventive Action After NIHL Reducing Costs of Hearing Loss • Audiometric test •Retest •Notification 0 2 4 6 8 10 12 14 16 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

45. 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

46. 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

47. Ear plug fit-testing methods

48. Reducing Costs of Hearing Loss OSHA Alliance: Best Practice Bulletin www.hearingconservation.org Additional Information www.howardleight.com

49. 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!"

50. Pre and Post-Test Fit-Testing as a Training Tool • “How well can users predict their attenuation after a short fit-testing training session?"