Fig. 4. An example of a frequency jump in e1 [recorded in interclavicular air sac pressure (ICAS)], in which fundamental frequency (f₀) jumps from approximately 525 Hz to 675 Hz within 5 ms. (A) Oscillogram (top) and spectrogram (bottom) of complete e1. (B) Detail of jump (time frame is indicated by broken lines in A) in which the oscillogram is superimposed on the spectrogram. The oscillogram shows that sound is not interrupted during frequency jumps. Although harmonic overtones are present in ICAS-recorded coo vocalizations, spectrograms here show only f₀, which is the sound component that radiates from the animal. Note that the shape of the sound waveform in the ICAS is different before and after the frequency jump. Spectrogram settings: time step, 1.8 ms; frame length, 25 ms; dynamic range, 10 dB. The signal has been pass-band filtered from 300 Hz to 2500 Hz.