Psychophysical tuning functions, dichotic stimuli, and pulsation thresholds

Abstract

Using a dichotic mode of stimulus presentation, four psychophysical tuning curves were obtained: input filter pattern, input extension pattern, output filter pattern, and output extension pattern [J. Verschuure, Acustica 49, 288–295 (1981)]. Stimulus parameters for all tuning functions were: durations 60 ms, rise/decay 10 ms, interstimulus interval (delta‐t) 0.00 ms (no overlap between pulsator offset and signal onset). Stimuli were presented in sequential pairs (pulsator then signal), alternating between ears; e.g., left ear (pulsator‐signal), right ear (pulsator‐signal), left ear (pulsator‐signal), etc. The alternation between ears was temporally controlled to insure no overlap (delta‐t = 0.00 ms) between signal offset in one ear and pulsator onset in the other. Pulsation thresholds were obtained by the method of adjustment for each of the four tuning patterns. Results indicate that pulsation threshold patterns could be perceived when the stimuli were presented dichotically, i.e., the perception of “continuity” was synthesized by central processes. Tuning patterns, generated with the dichotic stimuli and based on the centrally synthesized pulsation thresholds, appear to be similar to those in the literature. Contrasts of the four tuning patterns will be presented.