Fig. 6.

Example of participants' Syllable AM tapping phase, for a single presentation of the sentence “Mary Mary quite contrary” (Rhythm calibration by multi-timescale AMs). (a) Here, the actual time-course and distribution of participant taps (circles and crosses) is plotted with respect to the amplitude of the Syllable AM (green line). Each participant produces 4 taps, which occur around the 4 stressed syllables, “MA-”, “MA-”, “QUITE” and “-TRA” respectively. Note that each cycle (peak) of the Syllable AM corresponds to a single uttered syllable. Therefore the Syllable AM is an acoustic landmark for real speech events. (b) The same distribution of taps is now replotted with respect to the PHASE of the Syllable AM rather than its amplitude. Note that the peak of the Syllable AM corresponds to a phase value of 0 radians (mid-way up the y-axis), while the trough of the Syllable AM corresponds to phase values of −π/π radians. The circular equivalence of these two values explains the abrupt vertical cliffs in the phase plot. Note that the majority of participants' taps tend to occur within the temporal confines of a single AM cycle (−π to π radians), corresponding to the region of the increasing slope in the phase plot (solid black box).