Author(s): Liberman MC, Kiang NY
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Abstract The rate and phase of auditory-nerve response to tone bursts were studied as a function of stimulus level in normal and acoustically traumatized animals. The rate- and phase-level functions of normal auditory-nerve fibers are often separable into a low-intensity component (component I) and high-intensity component (component II), as defined by a dip in the rate function and a simultaneous abrupt shift in the phase function at stimulus levels near 90 dB SPL [10,12,9]. Baseline data are established by defining the relation between stimulus frequency and the characteristic frequency and spontaneous discharge rate of a fiber normally required for the appearance of these two components in the response. Abnormalities of the level functions are shown to occur in acoustically traumatized ears. Noise-induced threshold shift is often characterized by selective attenuation of component I. In some instances, it appears that component I has been eliminated, leaving a response which is identical in threshold, phase and maximum discharge rate to a normal component II. Results of single-unit labeling in such a case suggest that the selective attenuation of component I is associated with selective loss of the tallest row of stereocilia on the inner hair cells (IHCs). It is suggested that component I is normally generated through an interaction between the outer hair cells and the tall row of IHC stereocilia, while component II requires only the shorter row of IHC stereocilia.
This article was published in Hear Res
and referenced in Otolaryngology: Open Access