The use of mp3 players as a possible cause of NIHL

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The use of mp3 players as a possible cause of
NIHL

• Wouter Dreschler (w.a.dreschler_at_amc.nl)
• Academic Medical Centre, Amsterdam, The
  Netherlands
• Jan de Laat
• Leiden University Medical Centre, Leiden, The
  Netherlands

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Contents

1. Screening tests at the internet (www.oorcheck.nl)
2. Check of mp3-exposure at the internet
   (www.mp3check.nl)
3. Results in 100.000 users
4. A model for the sensitivity to MIHL
5. Conclusions

Contents
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1. Website Oorcheck.nl
Oorcheck.nl
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Online speech-in-noise tests

• Speech-in-noise tests
• Spectrum of masking noise is equal to speech
  spectrum
• Adjustable presentation level
• Adaptive procedure
• 2 dB steps up-down
• Fixed noise level
• SRT 50 correct recognition
• Average signal-to-noise ratio over stimuli

Oorcheck.nl
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Results as a function of age
Oorcheck.nl
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Subjective versus objective results
Oorcheck.nl
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2. Website mp3check.nl
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Technical measurents on HATS manikin

• Tested
• gt30 mp3-spelers
• different earphones
• four positions of the
• volume wheel
• different musical styles
• Effects
• coding strategy almost absent
• Musical style moderately strong
• Mp3-player large!
• Earphone very large !!

mp3check.nl
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Average output levelsof 103 fragments,
classified in 9 musical styles
mp3check.nl
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Max.output per musical style and mp3 player
mp3check.nl
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3. Results from 100.000 users
Results mp3check.nl
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Characteristics of mp3-use (n100.000)

• 22 of the users uses the upper 20 of the volume
  range
• 76 of the users listens less than 10 hours per
  week

Results mp3check.nl
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Levels of sound exposure (n100.000)

• The output levels are gt 90 dB(A) for 21 if the
  subjects
• However, these levels may be corrected for
  exposure duration
• Safe exposure 76 of the users
• lt80 dBA _at_ 40 h/w, lt83 dBA _at_ 20 h/w, lt86 dBA _at_ 10
  h/w, etc.
• Higher exposure 24 of the users

Results mp3check.nl
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The effects of musical style

• Differences in exposure levels for different
  musical styles

Results mp3check.nl
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4. A model for the sensitivity to MIHL
27-2-2010
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Risk assessment
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Hypotheses in risk assessment

• MIHL NIHL
• Levels gt 75 dBA may contribute to damage
• Exchange rate 3 dB
• Exposure calculated re. 40 hours/week
• Adapted risk model
• MIHL after 10 years of use
• Focus on HTL234
• lt 5 dB safe (green)
• 5-10 dB marginal (orange)
• gt 10 dB unsafe (red)
• Predictions based on ISO-1999 (P50)

Risk assessment
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Not just the output level !!
Risk assessment
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27-2-2010
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5 Conclusions
27-2-2010
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Conclusions
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Conclusions

• Unexpectedly, about 20-30 of young subjects have
  deteriorated hearing for speech in noise
• MIHL is a possible cause
• Mp3 players form a non-neglible part of the sound
  exposure in youngsters
• Therefore, there is need for action
• Limitation of max. Output levels (as in the EU)?
• Counseling and awareness
• Large-scale screening with a test sensitive for
  MIHL

Conclusions
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Thanks for your attention
Questions?
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Thanks for your attention
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Results as a function of age
Oorcheck.nl