Intracochlear Fluid Pressure and Cochlear Input Impedance from Push-pull Amplification Model

Abstract

Intracochlear fluid pressure and cochlear input impedance are simulated and compared with in-vivo physiological measurements. The objective of this work is to compare the calculations and measurements for the cochlear fluid pressure (P-ST) and related cochlear input impedance (Z(C)) with "push-pull" active cochlear model involving cochlear cytoarchitecture. Presented three-dimensional cochlear hydro-dynamic model is developed by implementing an active "push-pull" cochlear amplifier mechanism based on Y-shaped organ of Corti cytoarchitecture and using the time-averaged Lagrangian method. For the gerbil P-ST magnitude, the model results shows (i) the nonlinearity with 10 dB gain, (ii) the 2/3 octave shift in the active case, and (iii) the presence of peaks and valleys which are observed in gerbil in vivo measurement. Additionally, simulation results of chinchilla and cat cochlear vertical bar Z(C)vertical bar reflect overall trend of animal measurements, while the gerbil and human cochlear vertical bar Z(C)vertical bar are 10 dB lower (> 2 kHz) and 7 dB lower (< 2 kHz) than the measurements respectively.