Effective Duration of the Onset-Transient Cue to Auditory Localization
Jerry V. Tobias, Earl D. Schubert · The Journal of the Acoustical Society of America · 1959
The interaural time difference at the beginning and the end of a noise burst—labeled “transient disparity” for convenience—was varied independently of the ongoing disparity. By producing a transient cue which favored localization judgments to one side of the median plane and an ongoing cue which favored judgments to the other side, a trading relation was established, and the relative contributions of the two cues to localization were computed for a range of burst lengths. The transient cue was found to affect subject judgments for burst durations up to approximately 150 msec. For longer durations, the largest transient interaural time disparity employed (500 μsec) was too small to have any effect. For the range of duration explored −10 to 1000 msec—ongoing disparity “moves” the burst more readily than transient disparity. One hypothesis which may account for this relative effectiveness, i.e., for the apparent loss of information from the transient disparity cue, is that the relative importance of the two cues is directly proportional to the fraction of the total burst duration over which each is operative. From that hypothesis, a value of “effective onset duration” was calculated and found to lie between 2 and 4 msec. It is suggested that the inherent neural on-effect would shorten the value to approximately 1 msec. (This research was supported in part by the National Science Foundation.)