Binaural Interaction of Clicks of Different Frequency Content

Abstract

Observers were required to adjust the interaural time relation of dichotically presented clicks to place the click image in the median plane. A check on the adequacy of the adjustment was made by commutating the dichotic signals. If the image did not appear to shift location on commutation, the interaural time difference was recorded. The “standard” click was generated by ringing a band-pass filter set at 250–500 cps. The filter for the “variable” click was set either at the same or at one of four higher octave bands. The two clicks were adjusted to the same level of five different peak equivalent sound pressure levels. For small frequency separations only one clearly localizable click-image could be heard. At higher frequency differences there were two images, one sounding high and the other low in pitch-like quality. To place the high-pitched image in the center of the head, the high passband click was set to lead the low and was set to lag to place the image of low-pitch quality in the midline. An explanation of this peculiar phenomenon will be attempted.