Experimental design. The conditions of the three experimental parts are presented as relative Frequency against relative Time. (A) Parts 1 and 2. The Sound Onset Asynchrony (SOA) between the successive A-tones was 250 ms, corresponding to a presentation rate of 4 Hz. The SOA between the successive B-tones was 500 ms, corresponding to an SOA of 2 Hz. The SOAs linking the irregular ABA structure were set to 100 ms (A-B segment) and 150 ms (B-A segment), corresponding to 10 and 6.6 Hz rates, respectively. Four different degrees of Δf were opposed in part 1 (0 vs. 10-semitones) and part 2 (2 vs. 4-semitones). (B) Part 3. Independent presentation of A- and B-tone streams with Δf of 10-semitones. The presentation rates of the A- and B-tones corresponded to 8 Hz (SOA = 125 ms) and 4 Hz (SOA = 250 ms), respectively.