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RAAF Institute of Aviation Medicine
Real-world attenuation of foam earplugs.
Dr Adrian Smith
RAAF Institute of Aviation Medicine
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
RAAF Institute of Aviation Medicine
RAAF Institute of Aviation Medicine
RAAF Institute of Aviation Medicine
Measured noise Factory attenuation data Calculated at-ear noise
exposure
… assuming that the wearer gets full benefit of earplugs.
• 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.
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.
This is how deep to insert earplugs!
Aim
Document real-world attenuation of foam earplugs.
Determine whether training improves attenuation.
Method43 aircrew, attending AVMED for training
Asked to insert earplugs as normal.– Blinded to purpose of the study– Not coached or corrected– Technique recorded
Attenuation measuredOne-on-one training, plus 10-sec video clipsAttenuation re measured
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%
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 protectionof an ‘informed user’
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
What about those with “formal training”?
*
After training…
Importance of technique
** *
* p<0.001
*
*
Does the training benefit everyone?
One size fits all....
One size fits most....
Small
Large
Improvement P-value‘Formal instruction’ already 10.1 dB
0.81Self-taught 9.4 dBPilot 8.4 dB
0.41Non-pilot aircrew 10.5 dBNewly-qualified (<100 h) 11.1 dB
0.15Experienced (>1500 h) 7.3 dBConfident in technique 9.4 dB
0 96
Who benefits from training?Attenuation P-value
Before training 15 dB<0.001
After training 26 dB
10 dB improvement … so what?
Every 3 dB=
double sound pressure level
Sound pressure level↓
Noise exposure↓
Risk of NIHL3 6 9 12 15
dB f tt ti
Conclusions
Foam earplugs in the hands of untrained users are significantly less effective than factory specifications.
ADF pers likely over-exposed to noise.
Brief training intervention– Insertion technique, improved
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?
Thank you
Dr Adrian Smith
Specialist Aviation Medical Officer (Army)RAAF Institute of Aviation Medicine
[email protected]: 08 7383 3169
Foam earplugs:
more interestingthan you think!
Thank you
Dr Adrian Smith
Specialist Aviation Medical Officer (Army)RAAF Institute of Aviation Medicine
[email protected]: 08 7383 3169
