Fig. 5. Nest preparation sound produced by the Hawaiian sergeant fish, Abudefduf abdominalis. Sonogram (bottom) and oscillogram (middle) shows a train of eight individual pulses produced at regular intervals. Power spectrum (top left) of a single pulse (inset at top right) shows that nest preparation sounds are broadband, but with high energy components between 100 and 400 Hz. Power spectrum calculated by 128-point FFT (Hanning window). Spectral display settings are Hanning window, 128 point, 75% window width. Arrows on the single pulse show the beginning and end of the pulse to illustrate how pulse duration was measured.