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Noise and Advanced Hearing Protection Jim Wilt

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Noise and Advanced Hearing Protection Jim Wilt

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    2. Outline

    3. Military Vehicle Noise

    4. Military Vehicle Noise & Safe Exposure Limits

    5. Safe Noise Exposure Limits

    6. Current Double Hearing Protection

    7. Flight Deck Noise in Perspective

    8. Real-World Hearing Protection Explanation: The most meaningful way to look at earplug insertion depths was to consider each ear individually. Had each subject’s left and right earplug insertion depth been studied, the two (left / right) earplug insertion depths would have had to have been averaged together; or the minimum earplug insertion depth used; or the maximum earplug insertion depth used. These three options elicited a less clear picture of what occurred than looking at each earplug independently. 85% of subjects’ left and right earplugs were ?2 mm different for insertion depth (8 mm was the maximum difference between left and right earplug insertion depth). No correlation could be found between similar left / right earplug insertion depths and achieving optimum earplug insertion depth of =20 mm. Explanation: The most meaningful way to look at earplug insertion depths was to consider each ear individually. Had each subject’s left and right earplug insertion depth been studied, the two (left / right) earplug insertion depths would have had to have been averaged together; or the minimum earplug insertion depth used; or the maximum earplug insertion depth used. These three options elicited a less clear picture of what occurred than looking at each earplug independently. 85% of subjects’ left and right earplugs were ?2 mm different for insertion depth (8 mm was the maximum difference between left and right earplug insertion depth). No correlation could be found between similar left / right earplug insertion depths and achieving optimum earplug insertion depth of =20 mm.

    10. Real-World Hearing Protection 301 subject fleet survey findings: 75% issued questionable size - most given largest sizes 41% needed earcups maintenance301 subject fleet survey findings: 75% issued questionable size - most given largest sizes 41% needed earcups maintenance

    11. The Cost of Noise

    12. Re-Cap of Main Points so Far

    13. Goals: New Hearing Protection & Comm

    14. New Hearing Protection & Comm Tech

    15. Closing the Gap

    16. Help Us Help You

    17. Summary

    18. Backup Slides

    19. Earcup Foam Inserts (NAVAIR SBIR N01-162, Adaptive Technologies, Inc., David Clark Company) Product Description Intended Use: Improve passive noise reduction rating (NRR) in US Navy flight deck helmet earcups Primary User: Anyone using same earcup style Description: Foam that is custom shaped to fit inside earcups

    20. Tethered Custom Deep Insert Earplug (NAVAIR SBIR N01-162, Adaptive Technologies, Inc., Air Force Research Laboratory) Product Description Intended Use: Improve passive noise attenuation in US Navy flight deck headsets Primary User: Anyone using same earcup style Description: Solid, custom molded earplug that can be tethered to earcups

    21. Digital Noise Canceling Microphone (NAVAIR SBIR N01-162, Adaptive Technologies, Inc.)

    22. Active Noise Reduction (ANR) Earplugs (Air Force Research Laboratory, NAVAIR SBIR N01-162, Adaptive Technologies, Inc.) ANR earplug MIRE data presented in this report were measured in the trapped volume between the tympanic membrane and inserted end of earplug tip. This trapped volume was always less than 1 cc and in most cases less than 0.5 cc; for this small volume, a phase shift from the ANR earplug microphone was not considered to be an error factor. ANR earplug MIRE data presented in this report were measured in the trapped volume between the tympanic membrane and inserted end of earplug tip. This trapped volume was always less than 1 cc and in most cases less than 0.5 cc; for this small volume, a phase shift from the ANR earplug microphone was not considered to be an error factor.

    23. Miniature CEPs w/ Soft Core, Macromelt Earphone & Ear Canal Vent (USArmy Aeromedical Research Lab, NAVAIR SBIR N02-151, Commun. & Ear Protection, Inc.)

    24. Miniature CEP with Custom Molded Earplug (NAVAIR SBIR N02-151, Communications & Ear Protection, Inc.)

    25. Hear-through Miniature CEP (NAVAIR SBIR N02-151, Communications & Ear Protection, Inc.)

    26. Maintainer Noise Reduction Helmet (NAVAIR SBIR N0-161/N04-255, Air Force Office of Scientific Research STTR, Creare, Inc.,)

    27. Human-Shaped Earcups (NAVAIR (funded by Office of Naval Research), Air Force Research Laboratory

    29. Safe Noise Exposure Limits

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