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

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

2. Topics Leading vs Lagging Indicators Motivating Workers Continuous Monitoring Audiometric Testing Earplug Fit Testing

3. Hearing Conservation Metrics • Indicators for Hearing Loss: • Standard Threshold Shift • Temporary Threshold Shift • Recordable Hearing Loss • Dosimetry • In-ear Dosimetry • Personal Attenuation Level (PAR) • Hearing Loss Compensation

4. Hearing Conservation Metrics Lagging Indicators vs. Leading Indicators

5. Hearing Conservation Metrics • Indicators for Hearing Loss: • Standard Threshold Shift • Temporary Threshold Shift • Recordable Hearing Loss • Dosimetry • In-ear Dosimetry • Personal Attenuation Level (PAR) • Hearing Loss Compensation

6. Hazardous Noise Hearing Conservation Metrics 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

7. Hearing Conservation Metrics • Conduct audiometric testing during the work shift • TTS vs PTS

8. Hearing Conservation Metrics • Percentage of exposed workers with STS/year • Affected by: Duration of employment, Demographics • Recent analysis of large database: 1980-present: 1.5% per year • In non-noise exposed employees: roughly 1% • Current corporate policy: 1% rate per year, or equivalent to internal non-occupationally exposed population- ?Best Practice?

9. Hearing Conservation Metrics • Use Early Warning Flags • Identify individuals at risk for significant loss in future • Identify problem jobs/work areas

10. Age-Corrected STS Represents Significant Hearing Loss! Hearing Conservation Metrics • Study of industrial workers: • 52% of OSHA recordable STS cases (new definition) had compensable hearing impairment (AAOHNS criteria)! • Median time to develop recordable STS: approx. 10 years* * Rabinowitz et al. Impact of OSHA rule: recording hearing loss JOEM 2003

11. Hearing Conservation Metrics • So….. • Age-Corrected STS • is NOT • an “Early Flag”!

12. Hearing Conservation Metrics • Candidate “Early flags” (indicators) • 10 dB shift from baseline in avg 2,3,4KHz (not age-corrected) • 15dB shift from baseline (at least one frequency 1-6KHz) (Department of Defense) • 15dB shift from baseline (at least one frequency 1-6KHz) confirmed on second test (NIOSH) • Others: • 7dB shift 2,3,4KHz? • 5dB shift 2,3,4KHz?

13. Hearing Conservation Metrics • Compensable Hearing Impairment: • How many workers have absolute loss of >25dB avg 500,1K,2K,3KHz? • Useful for workers comp liability as well as need for workplace accommodation, etc. • Noise Levels- trends over time for individual departments.

14. Hearing Conservation Metrics In-Ear Dosimetry Fit Testing

15. Earplug Fit Testing • 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)

16. Earplug Fit Testing 0 dB 0 dB >33 dB EAR #1 EAR #2 EAR #3 How much protection?

17. Earplug Fit Testing 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 Attenuation in dB 50 40 30 20 10 0 -10 Good Fit vs Bad Fit

18. Earplug Fit Testing Loudness Balance (Real-Ear Attenuation Above Threshold)

19. Part 1: Both ears unoccluded This sets the baseline level for each ear, and measures any asymmetry. Part 2: Right ear occluded Attenuation for the right ear is measured. Part 3: Both ears occluded Attenuation for the left ear is measured. Test Sequence Result ~ Personal Attenuation Rating (PAR)

23. Measures real-world attenuation of any earplug • Fulfills requirement to ‘ensure proper fitting’ of earplugs and evaluate their attenuation • On-screen training videos • Administered anywhere, quiet room not required • Protected exposure level and safe exposure level calculated

24. Hearing Conservation Metrics OSHA Alliance: Best Practice Bulletin www.hearingconservation.org Additional Information www.hearforever.org

25. Noise Reduction Rating Hearing Conservation Metrics 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”

26. Hearing Conservation Metrics Published NRR

27. Hearing Conservation Metrics Personal Factors Gender Age Years in Noise Ear Canal Size Familiarity Model of Earplug Program Factors # Group Trainings # Personal Trainings

28. REDUCING COSTS / CLAIMS Hearing Conservation Metrics Published NRR Trying a second earplug often improves attenuation

29. “How well can users predict their attenuation after a short fit-testing training session?" Reducing Costs of Hearing Loss Hearing Conservation Metrics

30. Fitting Tips Ability to Predict Noise Reduction Reducing Costs of Hearing Loss Hearing Conservation Metrics

31. Hearing Conservation Metrics

32. Hearing Conservation Metrics

33. Hearing Conservation Metrics

34. Reducing Costs of Hearing Loss Hearing Conservation Metrics 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!"

35. Hearing Conservation Metrics 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)

36. 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

37. Reducing Costs of Hearing Loss Continuous Monitoring / In-ear-dosimetry

38. Reducing Costs of Hearing Loss Hearing Conservation Metrics Continuous Monitoring / In-ear-dosimetry • Mean Hearing Threshold (2k, 3k, 4kHz): 2000 – 2007 (N = 46) • Employees using continuous in-ear dosimetry starting in 2005

39. In-ear dosimetry as a Problem Solver Reducing Costs of Hearing Loss Hearing Conservation Metrics 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

40. Preventive Action After NIHL Hearing Conservation Metrics • 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

41. Reducing Costs of Hearing Loss Hearing Conservation Metrics 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

42. Training + Motivation

43. Training + Motivation Common Objections to Wearing HPDs “I already lost some of my hearing, so why should I wear them?” “Won’t I get an ear infection?” “Hearing protectors are uncomfortable to wear.” “I don’t need them! I am used to the 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.”

44. 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?

45. 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/honaaohn

46. 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

47. 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

48. Make Hearing Conservation Part of Your Everyday Life www.hearforever.org/honaaohn