Auditory pursuit tracking performance using level-changing noises with time

Abstract

This paper describes two experiments concerned with an auditory pursuit tracking. The stimuli are level-changing white noises. They consist of 60 and 61 constituent noises presented continuously, whose sound pressure levels are 42, 50, 58, 66, 74, 82 and 90dB. Exp. I had 4 stimulus-pattern conditions which differed from each other in the sequence and timing of appearances of 7 levels. One of these 4 conditions was used in Exp. II. Subject was instructed to push the button as quickly and correctly as possible, corresponding to the direction of intensity change of the stimulus. A response box was used with 7 buttons in a line in Exp. I, while in Exp. II with 9 including unused end buttons in order to remove the response cues at both ends. Reaction time (RT) was measured for the constituent noises. The results represent the relation between stimulus pattern and tracking difficulty. That is, mean RT is shortest when both direction and timing of intensity change of the stimulus are regular, and is longest when both are irregular. Also it means that the RT undergoes a systematic decrease with a corresponding increase in predictability the constituent noise has. This fact, especially the effect of predictability derived from the response cue, was confirmed in Exp. II.