Auditory Detection of an Unspecified Signal

Abstract

Listeners were required to detect an auditory signal against a background of “white noise.” The effects (1) of giving trial-by-trial information as to whether or not a signal was delivered, and (2) of giving the subject an opportunity to hear the signal before the test sequence began, were studied at two levels of signal energy. The results were analyzed within the context of the theory of signal detectability. Subjects who were given an opportunity to hear the signal before the test sequence began maintained a stable level of performance throughout the experimental session. On the other hand, subjects who were given no opportunity to hear the signal performed near chance level at the beginning of the session but showed gradual improvement as trials progressed. The effect of trial-by-trial feedback was surprisingly small in all groups. Near the end of the session, the signal was demonstrated to all subjects and the differences between the groups vanished.