Mechanics of the Sound Signal Processing in the Ear; Experiment and Simulation

شروع رویداد
سه‌شنبه ۲۴ مرداد ۹۶ ۱۰:۰۰
پایان رویداد
سه‌شنبه ۲۴ مرداد ۹۶ ۱۱:۳۰
مکان رویدادتهران
اضافه به تقویم
Mechanics of the Sound Signal Processing in the Ear; Experiment and Simulation
برگزارکننده‌ی رویداد
تماس با برگزارکننده
۰۲۱۸۸۶۲۸۹۳۶ - ۰۲۱۸۸۶۲۸۹۴۰ - ۰۲۱۸۸۶۲۸۹۴۵
گزارش
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جزئیات
مهلت ثبت‌نام
قیمت (تومان)
تعداد

توضیحات بیشتر

earing relies on a series of coupled electrical, acoustical and mechanical interactions inside the cochlea that enable sound processing. The cochlea is the spiral-shaped part of the inner ear where the fluid-borne vibrations are detected by the auditory sensors and then the information, in the form of neural signals, are transferred to the brain by the auditory nerves. A mathematical model of the cochlear response to sound over the entire spectrum will help us understand how important classes of signals are processed in the cochlea (such as speech and music) which can lead to better speech processing algorithms or cochlear implant electrical stimulation paradigms. The mechanical and electrical responses of the mammalian cochlea to acoustic stimulus are nonlinear and tuned. This is reflective of the electromechanical response of the outer hair cells (OHC) which are responsible for mediating the active process necessary for normal hearing. A comprehensive 3-dimensional nonlinear model of the cochlea is developed and it is utilized to interpret the experimental data and predict immeasurable quantities. This model is physiologically based in that electrical and mechanical elements of the cochlea are coupled explicitly through kinematic constraints and forces. We use the experimental data in conjunction with simulations to study nonlinear amplification in the cochlea. The sound-evoked voltage inside the scala tympani was measured for a range of frequencies and pressure levels. The experimental data show a notch in the voltage response at frequencies below the characteristic frequency (CF). This notch is seen to locate the onset of nonlinear amplification (in the frequency domain). Our model predicts the notch in the extracellular voltage as well as the phase relations observed from the experiments. The notch frequency corresponds to the resonance of the tectorial membrane (TM) and its limbal attachment in the radial direction unattached the OHC hair bundle (HB) in the model. At this resonance, the shearing force applied to the HB by the TM is minimum, resulting in smaller HB deflection, current transductions, and the notch in voltage. Our analysis of the model results shows that the phase shift around this notch introduces the correct phasing between mechanical and electrical responses for effective power amplification inside the mammalian ear

 

آدرس:تهران خ. کارگر، دانشکده فنی دانشگاه تهران، دانشکده مهندسی مکانیک، آمفی‌تئاتر دانشکده (ساختمان قدیم)