Depts. of Biomed. Eng. and Math., Boston Univ.
Laurel H. Carney
Dept. of Biomed. Eng., Boston Univ., 44 Cummington St., Boston, MA 02115
The intrinsically nonlinear character of auditory processing has long been the bane of linear models for the auditory periphery. A previous computational model [Carney, J. Acoust. Soc. Am. 93, 401--417 (1993)] for single auditory nerve fibers contained a feedback mechanism to vary the bandwidth of a narrow-band gammatone filter as a function of sound pressure level. That model simulated the compressive nonlinearity, including aspects of temporal and average discharge rate characteristics of low-frequency auditory nerve fiber responses. The proposed model extends the previous work; its architecture is motivated by the most recent empirical evidence on outer hair cell (OHC) physiology. The nonlinear narrow-band gammatone filter is replaced with a broad second-order bandpass filter [G. von Bekesy, J. Acoust. Soc. Am. 21, 245--254 (1949)] inside a feedback loop. The feedback path consists of a nonlinearity representing OHC transduction, followed by a lowpass filter for the cell membrane, and finally a nonlinearity representing OHC motility. A bank of such models allows representation of spatio-temporal discharge patterns across populations of auditory nerve fibers. [Work supported by The Whitaker Foundation and NIDCD.]