Recognition masking of auditory lateralization and pitch judgments

Two experiments determined backward and forward recognition masking functions in a lateralization task. Observers were presented with a 20-msec pure tone that differed in intensity to the two ears. The task was to indicate whether the tone came from the right or left. A second backward-masking tone interfered with the lateralization of the first test tone if it was presented within 180–250 msec of the first tone presentation. In contrast, a forward-masking tone had to be presented within 80 msec of the test-tone presentation in order to interfere with lateralization of the test tone. The results also showed that observers tended to lateralize the test sound in the direction of the masking sound if the test and masking sounds occurred within a 100-msec period. In a third experiment, subjects were required to identify a test tone as high or low in pitch in a recognition masking task. Although pitch judgments showed as much or more backward masking than lateralization judgments, significantly less forward masking was found in the pitch judgment task. Relative to lateralization judgments, observers showed a smaller tendency to judge the pitch of the test tone in the direction of the pitch of the masking sound. Subject Classification: [43]65.75, [43]65.54, [43]65.62, [43]65.58.