Fig. 6. Acoustic (top panels) and bilateral sonic muscle electromyogram (EMG; bottom panels) traces from a single evoked twitch and a voluntary call. The single twitch was evoked by stimulating the sonic nerve at 50 Hz and generated a two-part acoustic waveform. In the voluntary call, sound pulses from the right (R) and left (L) sonic muscle twitches are noted. Descriptions and mean durations of intervals A–H can be found in Tables 1, 2.