Central fatigue in a perstimulatory paradigm

Two experiments were performed to study perstimulatory auditory "central fatigue." In Exper. I, Ss tracked threshold for 13 min at .3, .6, 1,2,3, or 4 kc/s while being stimulated in the contralateral ear by a .5-kc/s tone at 75 db SPL. Bekesy tracings showed a significantly rising threshold at 2, 3, and 4 kc/s. In Exper. II, Ss tracked threshold for 13 min of a 3-kc/s pulsed tone while a .5-kc/s tone pulsed simultaneously at 75 db SPL in the contralateral ear. Results from previous central-masking research would predict an enhanced effect, while results from ipsilateral fatigue studies would predict a much reduced effect. The data showed virtually no effect at all, thus supporting a fatigue hypothesis.