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The use of mp3 players as a possible cause of NIHL. Wouter Dreschler ( w.a.dreschler@amc.nl ) Academic Medical Centre, Amsterdam, The Netherlands Jan de Laat Leiden University Medical Centre, Leiden, The Netherlands. Contents. Screening tests at the internet (www.oorcheck.nl)
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The use of mp3 players as a possible cause of NIHL Wouter Dreschler (w.a.dreschler@amc.nl) Academic Medical Centre, Amsterdam, The Netherlands Jan de Laat Leiden University Medical Centre, Leiden, The Netherlands
Contents • Screening tests at the internet (www.oorcheck.nl) • Check of mp3-exposure at the internet (www.mp3check.nl) • Results in 100.000 users • A model for the sensitivity to MIHL • Conclusions Contents
1. Website Oorcheck.nl Oorcheck.nl
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
Results as a function of age Oorcheck.nl
Subjective versus objective results Oorcheck.nl
Technical measurents on HATS manikin Tested: >30 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
Average output levelsof 103 fragments, classified in 9 musical styles mp3check.nl
Max.output per musical style and mp3 player mp3check.nl
3. Results from 100.000 users Results mp3check.nl
Characteristics of mp3-use (n=100.000) • 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
Levels of sound exposure (n=100.000) • The output levels are > 90 dB(A) for 21% if the subjects • However, these levels may be corrected for exposure duration • “Safe” exposure: 76% of the users [<80 dBA @ 40 h/w, <83 dBA @ 20 h/w, <86 dBA @ 10 h/w, etc.] • “Higher exposure: 24% of the users Results mp3check.nl
The effects of musical style Differences in exposure levels for different musical styles Results mp3check.nl
4. A model for the sensitivity to MIHL 27-2-2010 25 Risk assessment
Hypotheses in risk assessment MIHL = NIHL Levels > 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 < 5 dB: safe (green) 5-10 dB: marginal (orange) > 10 dB: unsafe (red) Predictions based on ISO-1999 (P50) Risk assessment
Not just the output level !! Change for permanent NIHL moderate change large change Very small change Risk assessment
27-2-2010 28
5 Conclusions 27-2-2010 31 Conclusions
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
Thanks for your attention Questions? 33
Results as a function of age Oorcheck.nl