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Diffusion Based Model for Noise-Induced Hearing Loss (NIHL)

Diffusion Based Model for Noise-Induced Hearing Loss (NIHL). 9 th EFAS Congress, 21.-24. June 2009, Tenerife, Spain Tron Vedul Tronstad and Olav Kvaløy SINTEF Department of Information and Communication Technology (ICT) Location: Trondheim, Norway Technology for a better society.

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Diffusion Based Model for Noise-Induced Hearing Loss (NIHL)

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  1. Diffusion Based Model for Noise-Induced Hearing Loss (NIHL) • 9th EFAS Congress, 21.-24. June 2009, Tenerife, Spain • Tron Vedul Tronstad and Olav Kvaløy • SINTEF Department of Information and Communication Technology (ICT) Location: Trondheim, Norway Technology for a better society

  2. Background • Two types of NIHL • Mechanical damage (>130dBC) • Metabolic fatigue (mid/high SPL, <130dBC)  Our focus • Outer Hair Cells (OHCs) are more vulnerable than other cells in the cochlea • Reactive Oxygen Species (ROS) damage OHCs through oxidative stress • Diffusion is possible to model with an electric analogy

  3. Model Assumptions/Requirements • Metabolic exhaustion is a damaging mechanism • Concentration of ROS over time damages the OHC • ROS production increases proportional to the power of the sound pressure (p2) • Diffusion of antioxidants from Stria Vascularis to OHC • Temporary Threshold Shift (TTS) is an indicator of the condition to the OHC • Accumulation of ROS causes TTS • Lowest sound pressure level giving TTS can also cause PTS (lowest reported is 65 dBA)

  4. The Cochlea Figure from: http://en.wikipedia.org/wiki/Image:Cochlea-crosssection.png

  5. The Cochlea with diffusion model • Concentration of compounds corresponds to voltages • Currents corresponds to flux of compounds • Volumes correspond to capacitors • Sources of ROS and antioxidants are equal to current and voltage sources • Diffusion resistance through membranes and volumes are described as resistors Simple model, but it has interesting qualities RT IROS VAntioxidant COHC Figure from: http://en.wikipedia.org/wiki/Image:Cochlea-crosssection.png

  6. Simulation Results • The shaded area (concentration × time) is used to predict damage • ISO1999 treats these two exposures as equal • Our model • Predicts damage for the continuous exposure • Show benefit of resting periods 2 x 88 dBA à 2 hours + 4 hours rest 88 dBA for 4 hours

  7. Summary • The concept has some interesting qualities • Resting periods are included • If correlation between concentration of ROS and TTS, the model can be individually calibrated • Possible expansions of the model is to include • Sound conditioning • Continued formation of ROS after exposure

  8. Thank you for your attention

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