Influence of a low-frequency tone on the sensitivity of primary auditory neurons: two fiber populations.

The influence of biasing low-frequency tone on the sensitivity of primary auditory nerve fibers to tone bursts at the characteristic frequency is determined. In 7% of the investigated fibers the sensitivity varied systematically with the position of the tone burst within the low-frequency tone period. In the remaining 93% of fibers this dependence was not observed. A comparison of the ratio of these numbers with the ratio of fibers from inner and outer hair cells leads to the suggestion that different responses stem from fibers innervating different types of hair cells.