A behavioral measure of the cochlear changes underlying temporary threshold shifts.

It is well documented that exposure to recreational noise may result in a temporary threshold shift (TTS) due to cochlear dysfunction. A forward-masking paradigm was used to estimate the relative contribution of inner hair cell (IHC) and outer hair cell (OHC) dysfunction to TTS. Eighteen normal-hearing adults completed a test battery before, immediately after, and one week after attending a loud music venue. Personal dosimeters recorded mean equivalent exposure levels of 99.0 dB A. Shortly after exposure, there was an average TTS of 10.8 dB at 4 kHz, and an average reduction in the estimated gain provided by the OHCs of 11.5 dB. Gain reduction correlated significantly with TTS. The results suggest that OHC dysfunction can account almost entirely for the raised thresholds. For the test battery conducted a week after exposure, all measures showed recovery to pre-exposure values.