Fig. 6. Courtship–female-visit sound produced by the Hawaiian sergeant fish, Abudefduf abdominalis. These sounds are composed of two pulse types: A and B. Sonogram and oscillogram (A) shows a train of pulses and a view of a single type A and type B pulse (inset). (B) Power spectra show that type A pulses are broadband without prominent harmonic intervals, while type B pulses have a pulse repetition rate of about 125 Hz with harmonic intervals up to 1 kHz. Power spectra calculated by 128 point FFT (Hanning window). Spectral display settings are Hanning window, 128 point, 75% window width. (C) Type A and B pulses are similar in the frequency domain, but type A pulses (filled circles) are much shorter in duration than type B pulses (open triangles).