Fig. 3. The normal song of Gryllus campestris. (A) Oscillogram of a chirp consisting of four pulses of increasing duration and amplitude. (B) Oscillogram of the chirp shown in A after filtering to remove frequencies below 7.5 kHz; this waveform has been amplified 16-fold relative to that in A. A and B use the same time scale. (C) Oscillogram of the fourth pulse of the chirp shown in A on an expanded time scale. (D) Oscillogram of the fourth pulse shown in B after filtering to remove frequencies below 7.5 kHz; this waveform has been amplified 32-fold relative to that shown in (C). (E) Plot of the cycle-by-cycle frequencies of the broad-band waveform shown in C (filled circles) and of the without-F_D (the song pulse after filtering out the peak at the dominant frequency F_D of the song pulse) waveform shown in D (open circles). The frequency scale for the broad-band waveform is on the left and that for the without-F_D waveform is on the right. C, D and E use the same time scale.