Fig. 1.

Representative hoot train of Batrachomoeus trispinosus. (A) Waveform (amplitude is in dimensionless arbitrary units) and (B) spectrogram (Hz) of 13 boatwhistle calls in a train of 36 s in duration. Box indicates the position of the individual call represented in C. (C) Power spectrum of an individual, representative hoot on an expanded time base, shown in the inset (scale bar represents 250 ms). (D) Close-up of boatwhistle waveform, showing fine-scale call structure. Sounds were recorded at 44.1 kHz.