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 (PST) and related cochlear input impedance (ZC) 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 PST 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 |ZC| reflect overall trend of animal measurements, while the gerbil and human cochlear |ZC| are 10 dB lower (> 2 kHz) and 7 dB lower (< 2 kHz) than the measurements respectively.