Simulation of the Multiphysical Coupling Behavior of Active Hearing Mechanism Within Spiral Cochlea

Nobel Laureate von Békésy first presented traveling wave theory, which explains the vibration mechanism of the basilar membrane (BM) of cochlea in 1960, and thus the mysterious veil of passive phonoreceptive mechanism of human cochlea was unveiled. However, the interpretation of active phonoreceptive mechanism of human cochlea has been a major medical problem for mankind. The active mechanism can be reflected in structures and the perilymph where a series of complex coupling nonlinear motion process is observed in the cochlea. Because the cochlea is small and complex, vibration data of the whole BM are not yet available from existing experiments. To address the problem, first, the motion equations of the organ of Corti (OHC) are established, and the circuit equations of the outer hair cells (OHCs) in the perilymph and the relationship between the motion of the outer hair cells and the electromotile force are derived. Then the active feedback force on the BM is obtained. Finally, an analytical-numerical combination model, where both macrostructures and microstructures of cochlea are included, is established. The model not only vividly depicts the spatial helical body and biological materials of the cochlea but also reflects the fluid-solid coupling nonlinear motion of cochlear structures in the electrical environment. Thus, the active hearing mechanism of cochlea is revealed.