Description

The mammalian inner ear is a sensory system with high sensitivity and sharp tuning in response to low intensity sounds. These important characteristics are due to the active feedback by outer hair cells (OHCs) that amplify the vibrations of the fluid-loaded cochlear partition. In order to simulate the dynamics of the cochlea in response to sounds, many cochlear models are formulated in the frequency domain or using a one-dimensional formulation to reduce the computational cost. However, some aspects of nonlinear cochlear mechanics can only investigated using a three-dimensional time-domain model. We present here the development of a novel time-domain model of the mammalian cochlea formulated using a state-space approach. A three-dimensional model of the intracochlear fluids is coupled to a structural model of the cochlear partition using a finite element framework. Moreover, electrical degrees of freedom represent the electrical degrees of freedom in the cochlear ducts and in the OHCs. The active feedback by OHCs is modeled by linearized piezoelectric relationships, whereas the nonlinearity of the OHC mechanoelectrical transduction channels introduces nonlinearity in the model. This computational framework is used to simulate the nonlinear response of the mammalian ear to sounds. After calibration using measurements using in vivo measurements of the response of the cochlea to sounds, the model can be used to test hypotheses regarding hearing mechanics to help us to improve our understanding of the biophysics and biomechanics of the mammalian ear.

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Modeling acoustic fluid-structure interaction in the cochlea in the time-domain

The mammalian inner ear is a sensory system with high sensitivity and sharp tuning in response to low intensity sounds. These important characteristics are due to the active feedback by outer hair cells (OHCs) that amplify the vibrations of the fluid-loaded cochlear partition. In order to simulate the dynamics of the cochlea in response to sounds, many cochlear models are formulated in the frequency domain or using a one-dimensional formulation to reduce the computational cost. However, some aspects of nonlinear cochlear mechanics can only investigated using a three-dimensional time-domain model. We present here the development of a novel time-domain model of the mammalian cochlea formulated using a state-space approach. A three-dimensional model of the intracochlear fluids is coupled to a structural model of the cochlear partition using a finite element framework. Moreover, electrical degrees of freedom represent the electrical degrees of freedom in the cochlear ducts and in the OHCs. The active feedback by OHCs is modeled by linearized piezoelectric relationships, whereas the nonlinearity of the OHC mechanoelectrical transduction channels introduces nonlinearity in the model. This computational framework is used to simulate the nonlinear response of the mammalian ear to sounds. After calibration using measurements using in vivo measurements of the response of the cochlea to sounds, the model can be used to test hypotheses regarding hearing mechanics to help us to improve our understanding of the biophysics and biomechanics of the mammalian ear.