High-frequency sensitization of the acoustic reflex.

High-frequency sensitization of the acoustic reflex was studied in 10 normal-hearing subjects. The procedure involved pairing a subreflex 6000 Hz sensitizing tone with activating frequencies of 500, 1000, and 2000 Hz. Both threshold and growth of amplitude of the acoustic reflex were examined. Acoustic reflex threshold was reduced by an average of 10 to 12 dB in the presence of a 6000 Hz sensitizing tone, an amount significantly less than previously reported in similar investigations. Variations in the method used to adjust the presentation level of the high-frequency sensitizing tone probably account for these differences. Growth of acoustic reflex amplitude was also found to be influenced by sensitizing stimulation, with the greatest effect occurring near acoustic reflex threshold.