Onset coding of spatial information in trains of identical transients

In a study of the effects of onsets in lateralizing bursts of noise, Tobias and Schubert [J. Acoust. Soc. Am. 31, 1595–1605 (1959)] demonstrated that, depending on the duration of the ongoing noise burst, it takes anywhere between 4 to 35 times as much onset interaural time disparity to offset ongoing disparities. They, therefore, demonstrated that onsets do not necessarily provide the major cue to auditory localization. In the present study, onset and ongoing information in a lateralization paradigm is set in spatial conflict to determine the amount of onset interaural difference of time (IDT) necessary to offset ongoing IDTs of transient trains of various durations. The major difference between this study and the Tobias and Schubert study was that this study used identical transients [e.g., interclick interval (ICI) = 1.5 to 2 ms corresponding to a 500‐ to 750‐Hz tone] and not noise bursts. Unlike the Tobias and Schubert study, it was found in this study that a single dichotic click could easily lateralize a contralateral transient train of up to 200 clicks; producing the sensation of a tone lateralized to the position of the initial event. Various ICIs and ongoing durations were tested. In such a context, the precedence effect, the Franssen illusion, and the formation of auditory objects will be discussed. [Work supported by NSE and NIH.]