Figure 1
Quasi-steady-state auditory stimuli.
The quasi-steady-state auditory stimuli, presented at a comfortable listening level (~80 dB SPL) through binaural earphones, consisted of trains of 1 ms monotone pulses (101 pulses for each train, i.e., P1, P2, …, P101). Two types of train, i.e., descending train and ascending train, are respectively marked in blue and red. In the descending train, the inter-pulse intervals (IPIs), which were changed from 10 ms to 1000 ms, were 1000/100 ms between P1 and P2, 1000/99 ms between P2 and P3, 1000/98 ms between P3 and P4, …, 1000/1 ms between P100 and P101. In this case, the stimulus frequencies were 100, 99, 98, …, 1 Hz for the consecutive pulses. In the ascending train, the IPIs, which were changed from 1000 ms to 10 ms, were 1000/1 ms between P1 and P2, 1000/2 ms between P2 and P3, 1000/3 ms between P3 and P4, …, 1000/100 ms between P100 and P101. The stimulus frequencies were 1, 2, 3, …, 100 Hz for the consecutive pulses in this type of train.
