Real world attenuation of foam earplugs- smith

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Real world attenuation of foam earplugs- smith

  1. 1. RAAF Institute of Aviation Medicine Real-world attenuation of foam earplugs. Dr Adrian Smith RAAF Institute of Aviation Medicine
  2. 2. RAAF Institute of Aviation Medicine Noise-induced hearing loss • Common occupational hazard – Across industries – Global • Costs – Australia, 24% of OH&S claims in last 10 yrs – $$: compensation – $$: lost productivity – In Australia, $11 billion each year
  3. 3. RAAF Institute of Aviation Medicine
  4. 4. RAAF Institute of Aviation Medicine
  5. 5. RAAF Institute of Aviation Medicine
  6. 6. Measured noise Factory attenuation data Calculated at-ear noise exposure
  7. 7. • Roll earplug into a crease-free cylinder. • Pull Back ear by reaching over head with free hand, gently pull top of ear up and out. • Insert earplug deep into ear canal. • Hold until it fully expands. • Visual check. The earplug should not be visible from the front. • Acoustic check. Earplugs should block enough noise that covering your ears does not result in a significant difference.
  8. 8. But… Most earplug users do not receive formal training to insert earplugs. Start of training. “These are earplugs. t them in your ear when you are around loud noise”. End of training.
  9. 9. This is how deep to insert earplugs!
  10. 10. Aim Document real-world attenuation of foam earplugs. Determine whether training improves attenuation.
  11. 11. Method 43 aircrew, attending AVMED for training Asked to insert earplugs as normal. – Blinded to purpose of the study – Not coached or corrected – Technique recorded Attenuation measured One-on-one training, plus 10-sec video clips
  12. 12. Demographics Aircrew – Pilots, 24 (56%) – Non-pilots, 19 (44%) Experience – Junior (1-100 hr), 53% – Experienced (101-1500 hr), 28% – Very experienced (>1500 hr), 19%
  13. 13. ANSI S12.6-1997 Earplugs inserted under direct vision of a trained audiologist. Earplugs inserted by naïve wearers, following manufacturer’s instructions. AS1270:2002 Optimum protection Typical protection of an ‘informed user’
  14. 14. I S12.6-1997 Optimum performance, inserted under direct control of trained audiologist. NRR 32 dB 270:2002 Typical performance achievable by 80% of ‘informed users’. SLC80 25 dB s study. Performance of typical population of users. SLC801 18 dB
  15. 15. What about those with “formal training”?
  16. 16. *
  17. 17. After training…
  18. 18. Importance of technique
  19. 19. ** * * p<0.001
  20. 20. *
  21. 21. *
  22. 22. Does the training benefit everyone?
  23. 23. One size fits all....
  24. 24. One size fits most.... Small Large
  25. 25. Improvement P-value ‘Formal instruction’ already 10.1 dB 0.81 Self-taught 9.4 dB Pilot 8.4 dB 0.41 Non-pilot aircrew 10.5 dB Newly-qualified (<100 h) 11.1 dB 0.15 Experienced (>1500 h) 7.3 dB Confident in technique 9.4 dB Who benefits from training? Attenuation P-value Before training 15 dB <0.001 After training 26 dB
  26. 26. 10 dB improvement … so what? Every 3 dB = double sound pressure level Sound pressure level ↓ Noise exposure ↓ 3 6 9 12 15
  27. 27. Conclusions Foam earplugs in the hands of untrained users are significantly less effective than actory specifications. ADF pers likely over-exposed to noise. Brief training intervention – Insertion technique, improved
  28. 28. Take-home messages Earplugs are not intuitive to use. Earplugs need formal, structured training – Improved attenuation – Reduction in occupational noise exposure – Reduction in risk of noise-induced hearing loss AVMED training module: Roll. Pull. Push. Hold. Check. Target training or different earplugs?
  29. 29. Thank you Dr Adrian Smith Specialist Aviation Medical Officer (Army) RAAF Institute of Aviation Medicine adrian.smith14@defence.gov.au Tel: 08 7383 3169
  30. 30. Foam earplugs: more interesting than you think!
  31. 31. Thank you Dr Adrian Smith Specialist Aviation Medical Officer (Army) RAAF Institute of Aviation Medicine adrian.smith14@defence.gov.au Tel: 08 7383 3169

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