Tinnitus and neural activity.

The spontaneous discharge rates of auditory nerve fibers were measured in a group of normal chinchillas and in a group of chinchillas with high-frequency, noise-induced hearing loss. In contrast to normal units, the high-frequency units in the noise-exposed animals tended to have elevated spontaneous discharge rates, high thresholds, and a lack of two-tone inhibition. The change in spontaneous discharge rate across the distribution of nerve fibers is related to models of tinnitus and to human psychophysical data.