Frequency selectivity of single auditory-nerve fibers in response to broadband noise stimuli

Abstract

The tuning of single auditory nerve fibers in the rat response to broadband noise was studied in a large sound intensity range. Pseudorandom noise was used as stimuli and the cross spectrum between a period histogram of the noise and a period of the noise was used as an approximation of the transfer function from sound to the modulation of the neural discharge rate. In units with a CF [characteristic frequency] higher than 1000 Hz, the cross spectrum (at 10 dB points) invariably increased as the stimuli intensity increased and the center frequency decreased. The few units studied with CF below 1000 Hz seemed to undergo somewhat less change in width. The cross correlograms of all fibers with a characteristic frequency (CF) below 5 kHz showed a damped oscillation the duration of which decreased as stimuli intensity was increased. The similarity between the nonlinearity shown here and that shown in measurements of basilar membrane motion using the Moessbauer effect was discussed.