Figure 9.

A. An enlarged view of a section of Figure 8 (soprano 2) showing the integrated EMG from LD and the sonogram of the first held note of the aria finale exercise. This reveals phase locking between activity in the muscle and the pitch oscillations of the vibrato. B,C. Power spectra of the integrated EMG traces for LD and SCM for this note as sung by soprano 2 and mezzo 1. The prominent peaks just above 5 Hz match the vibrato frequency. Both singers have a strong signal for LD. Although mezzo 1 also shows a large peak for SCM, this is very weak for soprano 2 (arrow).