Determining Protected Exposures for Noise-Exposed Workers Theresa Y. Schulz, PhD. Lt. Col. USAF (ret.)

1. Determining Protected Exposures for Noise-Exposed Workers Theresa Y. Schulz, PhD.Lt. Col. USAF (ret.)

2. Agenda • Background • NRR • Fit-testing studies • Fitting HPDs • Motivation

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

4. Background • 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)

5. Background • 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)

6. Background In the United States, 76% of noise-exposed workers need no more than 10dB of protection. 90% need no more than 15dB of protection.

7. Noise Reduction Rating(NRR)

8. Noise Reduction Rating

9. 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)

10. 0 dB 0 dB 33 dB EAR #1 EAR #2 EAR #3 How much protection?

11. 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

13. 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.

14. Noise Reduction Rating • NVLAP-Accredited Labs San Diego, CA Indianapolis, IN State College, PA

15. 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)

16. Noise Reduction Rating – in the real world Real-World Attenuation≠ NRR 192 users of a flanged reusable earplug ~ 27 NRR 50 NRR = 27 Multiple-Use Earplug 40 30 20 Attenuation in dB 10 0 -10 From Kevin Michael, PhD and Cindy Bloyer “Hearing Protector Attenuation Measurement on the End-User”

17. 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

18. 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

19. Noise Reduction Rating • Three New Labels

20. Noise Reduction Rating • The New System: A Range • Represents a range of expected protection • Uses a new ANSI-standard (S12.6-2008) lab testing to generate the attenuation ratings • New NRR will provide an indication of how much attenuation minimally-trained users[the lower number] versus highly-motivated trained users [the higher number] can be expectedto achieve • For some hearing protectors, the spread of this range may be quite significant

21. Noise Reduction Rating • Current vs. Proposed NRR

22. Noise Reduction Rating • Current vs. Proposed NRR

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

24. 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%

25. Noise Reduction Rating • Will OSHA 29 CFR 1910.95 change? • OSHA has not announced any proposed changes to the Occupational Noise Standard • OSHA will presumably respond to the revised NRR label by issuing a field directive or technical memorandum, informing its compliance officers how to deal with the new two-number NRR range

26. Noise Reduction Rating • Will the new rating methods favor earplugs or earmuffs? • While a well-fit foam earplug generally has greater attenuation than most earmuffs, earmuffs are inherently easier to fit for most users • There is less variability in the fit of earmuffs • Overall range of attenuation for earmuffs will usually be tighter and often higher, than earplugs • Workers should be offered a choice of earplugs, bands and earmuffs that meet the requirements of the work environment

27. Noise Reduction Rating • Earplug Fit Testing • Provides an accurate,real-world picture of hearing protector effectiveness. • Identify if hearing protection users are: • Receiving optimal protection • Require additional training • Need to try a different earplug style

28. Earplug Fit-testing • As a problem solver: • Derating Schemes • One-on-One Training • HPD Selection • NRR Change

29. Field Verification – Fit-Testing 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

30. Ear plug fit-testing methods

31. Reducing Costs + Claims OSHA Alliance: Best Practice Bulletin www.hearingconservation.org Additional Information www.howardleight.com

32. Earplug fit-testing as a Problem Solver Reducing Costs + Claims • 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)

33. Review of some fit-testing studies

34. Noise Reduction Rating – in the real world 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”

35. Fit-testing Studies Published NRR

36. Fit-testing Studies Personal Factors Gender Age Years in Noise Ear Canal Size Familiarity Model of Earplug Program Factors # Group Trainings # Personal Trainings

37. REDUCING COSTS / CLAIMS Fit-testing Studies Published NRR Trying a second earplug often improves attenuation

38. Self-Efficacy Pilot Study • “How well can users predict their attenuation after a short fit-testing training session?”

39. Pilot Study Pilot study • Subjects: 17 construction workers with varied HPD experience levels • Equipment: VeriPRO earplug fit-test system • HPD: Volunteers • Process: 2-4 Quick Check fits where employee sees feedback of exact PAR • Subjects

41. Pilot Study • Data show improved PARs! • Results • Initial RE=19 LE=22 • Final RE=29 LE=27 • Average improvement 7.5 dB

42. Pre and Post-Test Pilot Study • How would you rate your ability to fit your earplugs? • 1 2 3 4 5 • Don’t know how I do OK Expert • Pre- and Post-Test

43. Pilot Study 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

44. Pre and Post-Test Pilot Study • “How much noise do you think your earplugs block?” • Self-Efficacy • 76% (13 of 17) judged attenuation as HIGHER post-test

45. Pre and Post-Test Pilot Study • Are you better able to assess the effectiveness of your earplugs after VeriPRO fit-testing? • 1 2 3 4 5 • No Maybe No change Improved Yes • Post-Test 64% (11 of 17) rated their abilityHIGHER post-test

46. Pre and Post-Test Pilot Study • “How well can users predict their attenuation after a short fit-testing training session?"

47. Pre and Post-Test Pilot Study 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

49. Risk Management

50. Risk Management • Indicators for Hearing Loss: • Standard Threshold Shift • Temporary Threshold Shift • Recordable Hearing Loss • Dosimetry • Labeled NRR (derated?) • In-ear Dosimetry • Personal Attenuation Level (PAR)