A time-domain digital cochlear model

The author presents a digital time-domain model of the human cochlea designed to represent normal auditory functioning and to allow for degradation related to auditory impairment. The model consists of the middle ear, the mechanical motion of the cochlea, and the neural transduction of the inner hair cells. The traveling waves on the cochlear partition are represented by a cascade of digital filter sections, and the cochlear micromechanics are represented by a second filter that further sharpens the excitation to the inner hair cells. The neural firing rate is determined by the sum of the outputs of multiple fibers attached to each inner hair cell, with the fiber neurons having firing characteristics representative of low- and high-spontaneous-rate fibers. The signal processing cochlear model incorporates dynamic-range compression by adjusting the Q of each cochlear filter section and second filter in response to the second-filter velocity and the averaged neural firing rate. Examples of the model response to impulse and tone-burst stimuli and to synthetic speech are presented