Mechanical and electromotile characteristics of auditory outer hair cells

The passive and active properties of the cochlear outer hair cell are studi ed. The outer hair cell is currently considered the major candidate for the active component of mammalian hearing. Understanding of its properties may explain the amplification and sharp frequency selectivity of the ear. To a nalyse the cell behaviour, a model of a nonlinear anisotropic electro-elast ic shell is used. Using the data from three independent experiments, where the mechanical strains of the cell are measured, estimates of the cell wall in-plane Young's moduli and Poisson's ratios are given, as well as estimat es of three modes of bending stiffness. Based on these estimates and data f rom the microchamber experiment, where the cell is under the action of tran smembrane potential changes, the characteristics of the outer hair cell act ive behaviour are found. These characteristics include the coefficients of the active force production per unit of the transmembrane potential change and limiting parameters of the electromotile response for extreme hyperpola risation and depolarisation of the cell. The obtained estimates provide imp ortant information for the modelling of organ-level cochlear mechanics.