ASA 127th Meeting M.I.T. 1994 June 6-10

2aPP19. Temporary threshold shift: Peripheral and central measures.

Chryssoula Thodi

Donald Gans

School of Speech Pathol. and Audiol., Kent State Univ., Kent, OH 44242

Although the cochlea has been established as a primary site of auditory fatigue, contributions to temporary threshold shift (TTS) by the central auditory system have been debated by researchers. The present study investigated TTS in gerbils following a short-duration, moderate intensity exposure to pure tones. TTS was measured by tone burst-evoked VIIIth nerve action potentials, cochlear nucleus and inferior colliculus single unit responses, and inferior colliculus population-evoked responses. The TTS measured at the level of the cochlea was not significantly different from the TTS measured at the cochlear nucleus or the inferior colliculus levels. The stimuli used in this study allowed for a recording of VIIIth nerve action potential that was reflective of sensitivity changes in a specific frequency area. It was concluded that when frequency specific stimuli are used to evaluate thresholds, exposure to moderate intensity, short duration tones results in similar degrees of TTS measured in peripheral and central levels of the auditory pathway.