NTT Human Interface Labs., 1-2356, Take Yokosuka-shi, Kanagawa 238-03, Japan
TNO Inst. for Perception, Soesterberg, The Netherlands
Possible effects of onset or offset dominance for pitch information are investigated with the same experimental approach, which clearly showed the familiar onset dominance in the perception of binaural cues [Houtgast and Aoki, J. Acoust. Soc. Am. Suppl. 1 87, S64 (1990)]. A brief stimulus, with a duration of 5, 10, 20, or 40 ms, is subdivided in two parts with durations T[sub 1] and T[sub 2], each part consisting of a sinusoidal signal of either 1 or 2 kHz. The measuring paradigm aims at assessing the critical ratio T[sub 1]/T[sub 2] for which both parts contribute equally to the overall sensation of pitch for these brief stimuli. This critical ratio is found to be greater than one, indicating a dominance of the pitch information presented in the later part of the stimulus. The data can be summarized in a weighting function: the perceptual weight of the pitch information as a function of time before signal offset. This weighting function shows a peak of enhanced weight for the last few milliseconds just before stimulus offset, in contrast with the enhanced weight for the first few milliseconds following stimulus onset as found previously in case of binaural cues.