Figure 1.

Schematic representation of stimuli and two types of auditory percepts. A, A sound sequence (a total of 90 s) of a triplet tone was presented in the perceptual switching task. Participants performed this task at either Δf ≈ 2 or 6 semitones. H and L stand for high- and low-frequency tones. B, Participants pressed a button with their left thumb when they perceived subjective changes from one stream (S1, LHL-LHL-…) to two streams (S2, L-L-… and H—H—…) or those from S2 to S1.