Power dissipation in the Organ of Corti

Abstract

In the cochlea, acoustic energy is transmitted toward the apex through the vibrations of a viscoelastic partition known as the organ of Corti complex. The dimensions of the vibrating structures range from a few hundred micrometers to a few micrometers. Vibrations of micro-structures in viscous fluid are subjected to energy dissipation. Because the viscous dissipation is considered to be detrimental to the function of hearing—sound amplification and frequency tuning, the cochlea is believed to use cellular actuators to overcome the dissipation. We have developed a computational model of the cochlea that incorporates viscous fluid dynamics, organ of Corti micro-structural mechanics, and electro-physiology of the outer hair cells. The model is validated by comparing with experimental results in the literature, such as the viscoelastic response of the tectorial membrane, and the cochlear input impedance. Using the model, we investigated how dissipation components in the cochlea affect its function. Our results suggest that most energy dissipation occurs within the organ of Corti complex, not in the scalar fluids. Our results suggest that appropriate dissipation enhances the tuning quality by confining the spread of energy from the amplification site.