MODELING INDIVIDUAL VARIABILITY IN COCHLEAR REFLECTANCE

Measurements of cochlear reflectance (CR) exhibit considerable variability across individual ears, similar to other measures of the peripheral auditory system (PAS). A mathematical model of the acoustics and mechanics of the PAS was fit to individual CR measurements in an attempt to account for sources of individual variability. The ear-canal section of this model is the concatenation of conical sections. The middle-ear section is a two-port network with lumped elements. The cochlear section is a tapered transmission line with a cochlear amplifier (CA) implemented by regions of negative damping. CR calculated for the model was compared to individual measurements from 24 ears with audiometric thresholds ranging from-5 to >60 dB HL. Model parameters associated with middle-ear and cochlear sections had little or no significant correlation with threshold, except for the CA-gain parameter, which had a highly significant correlation. This observation supports the validity of our modelling and fitting methods. Our ability to fit model parameters to individual ears is still being developed, but is expected to have clinical relevance in identifying possible middle-ear or inner-hair cell contributions to hearing loss.