Simulation of a Cochlear Model as a Descriptive Tool for Normal and Abnormal Auditory Functioning Miriam Furst-Yust Azaria Cohen, Vered Weisz, Noam Elbaum, Yaniv Halmut, Dan Mecrantz, Oren Bahat, and Udi shtalrid Dept. of Electrical Engineering-Systems Tel Aviv University

Clinical Audiometric Tests Audiograms Speech Discrimination Tests Otoacoustic Emissions

Audiometric Diagnosis Conductive or Sensorineural Hearing Loss Cochlear or Retrocochlear Hearing Loss Inner Hair Cells or Outer Hair Cells Loss ? The amount of Outer hair Cell Loss ?

Can a Cochlear model help in Audiometric Diagnosis ?

The Ear

Traveling Waves Tonotopic map of the Cochlea

Basilar Membrane Motion + Outer Hair Cells Amplification Outer Hair Cell

Cochlear Model One dimensional model Based on fluid dynamics

Outer Hair Cell Model Electromotile model OHC adds to basilar membrane pressure

Middle Ear Model Oval window Piston based model Outer earMiddle ear microphone Incudostapedial joint TM

Cochlear Model Equations Non Linear OHC motility Non Linear Basilar Membrane Motion OHC Index

Boundary & Initial Conditions Otoacoustic Emissions

Cochlear Representations of Tones Cochlear representation

Cochlear Representation of Chirp INPUT OUTPUT Input Signal : Chirp 1-3 KHz Normal Cochlea OHC Loss

Cochlear Representation of a click Stapes Apex Stimulus 100u s Healthy CochleaOHC Loss

Representation of a word Input Signal: The word “SHEN” INPUT OUTPUT Normal Cochlea OHC Loss

Cochlear Representation of a Noisy Word Input Signal: The word “SHEN” with Noise INPUT OUTPUT Normal Cochlea OHC Loss

Otoacoustic Emission

Introducing cochlear “ roughness ”

Model Prediction: Excitation Patterns Normal Cochlea No Active Outer Hair Cells Damaged Cochlea

Estimated Audiograms Normal OHC activity Partial damaged OHC No OHC activity

Estimated Audiograms

Simulated Audiograms Partial OHC activity with “roughness” Normal OHC activity with “roughness”

Damaged cochlear response

Partial OHC Loss Measured Audiogram Model Prediction

Non Linear Properties

Equal Loudness Countours

Non Linear Respomse טון בודד – פילטרים D=2.3cm CF=488Hz D=1.8cm CF=1074Hz

Basilar Membrane Gain

Response to Two Tones: Combination Tones TimeFrequency Input = 2kHz kHz; Equal level Healthy Cochlea