The results of this study, based on evoked responses and single-neuronal responses, reveal that there is a central involvement in auditory fatigue. In these experiments, cochlear potentials (microphonic and whole-nerve action potential) and inferior colliculus electrical responses were simultaneously obtained before and after excessive sound exposure. In general, sound exposure produced a greater reduction of the collicular evoked responses than of the cochlear microphonics and action potentials. Recordings from single neurons support the evoked-response findings.