Analytical predictions of auditory-nerve response to noise-modulated pulsatile electrical stimulation

Abstract

One factor that may impede speech recognition by cochlear implant subjects is that electrically stimulated auditory nerves respond with a much higher level of synchrony than is normally observed in acoustically stimulated nerves. Thus, the response patterns received by higher processing centers are likely to be substantially different from those generated under normal acoustic stimulation. These differences may form the basis for a degradation of speech understanding since the patterns generated under electrical stimulation may be interpreted incorrectly by higher processing centers. Based on recent findings, the implant research community has suggested several techniques to mitigate this synchrony, which may in turn provide some implanted individuals with improved speech recognition. In this work, the inter-stimulus interval histogram (ISIH) is utilized to compare the response of an electrically stimulated auditory nerve with that of an acoustically stimulated nerve of a cat. The ISIH data were generated from a stochastic model of the cochlea with noise-modulated pulsatile stimulation. Simulated ISIHs are presented along with corroborating analytical predictions of the results. When compared to an acoustically generated ISIH, these data indicate that the addition of noise may provide more natural neural responses to electrical stimuli. [Work supported by NSF.]