Frequency selectivity of the peripheral auditory analyzer studied using broad band noise.

The sharpness of the frequency tuning of single auditory nerve fibers was studied in the rat on the basis of responses to broad band noise. The cross-spectra between the sound stimulus and the sound-to-stimulus locked discharge rate were used as estimates of the transfer functions of the peripheral auditory analyzer. The sharpness of the tuning obtained in that way was measured as Q3dB and Q10dB. It was found that these Q-values decreased with increasing stimulus intensity but that the decrease was different when it was based on measurements at 3 dB points of the obtained transfer functions compared with measuring it at 10 dB points. The change in width was less for fibers with low CF. In all the fibers studied the frequency of maximal response (CF) decreased with increasing sound intensity. The implication of these findings for pitch perception and for noise induced hearing loss is discussed.