Prediction of Click Responses of Cochlear Nerve Fibers from Responses to Sinusoidal Stimuli

Abstract

A method for deriving tuning curves of single cochlear nerve fibers based upon a phase-locking response criterion [Littlefield el al., J. Acoust. Soc. Am. 51, 93 (1972)] yields gain and phase information as a function of the frequency of the stimulating tone. For a range of low-level and low-frequency stimuli, the response of cochlear nerve fibers has been shown to be consistent with a number of criteria for linearity [Littlefield el al., J. Acoust. Soc. Am. 54 (1973) (in press)]. If system linearity is assumed, measurements of gain and phase at discrete frequencies n/T, where n is a positive integer, can be used to predict the Fourier series of the response to any periodic stimulus of period T. By this method, we have calculated theoretical responses of low CF cochlear nerve fibers to periodic click trains, using gain and phase measurements taken within the range of stimulus conditions that have been found to produce responses consistent with a linear system hypothesis. Examples of gain and phase curves and click responses calculated from them will be presented and compared with directly obtained click responses. These comparisons may assist in evaluating linear and nonlinear properties of neural excitation. [This research was supported by PHS research grants from the National Institutes of Health.]