ASA 126th Meeting Denver 1993 October 4-8

2aPP2. The effects of level and frequency region on the recovery of overshoot.

Gary J. Overson Sid P. Bacon

Psychoacoust. Lab., Dept. of Speech and Hear. Sci., Arizona State Univ., Tempe, AZ 85287-1908

The term ``overshoot'' refers to the finding that the threshold for a brief signal can be higher when that signal is presented shortly after masker onset than when it is delayed by a few hundred ms. Overshoot can be reduced or eliminated by presenting a stimulus (precursor) prior to masker onset. The ``recovery of overshoot'' can be examined by varying the delay between the offset of the precursor and the onset of the masker. The purpose of experiment 1 was to evaluate this recovery at two (masker and precursor) levels, one relatively high and one relatively low. Overshoot was first measured as a function of masker level in order to choose two fairly disparate levels that produced nearly equivalent amounts of overshoot. Recovery functions were then measured at those levels. In general, there was little difference in the recovery at the two levels. In experiment 2, the precursor was sectioned into two bands, one on either side of the 4.0-kHz signal frequency. Recovery was measured separately for each band, while the other band was presented continuously. There was a tendency for the recovery to depend more upon the band above the signal frequency, suggesting that that region may be most important for overshoot. [Work supported by NIDCD.]