Fig. 1. (A) Oscillograms showing the gross temporal structure of standard synthetic advertisement calls of H. chrysoscelis (top) and H. versicolor (bottom). (B) Oscillograms with an expanded time base showing two pulses from six synthetic calls. Left column: H. chrysoscelis with the 2.4 kHz carrier frequency; pulse rates were (from top to bottom): 40, 50 (the standard rate) and 75 pulses s^–1. Right column: H. versicolor with the 2.2 kHz carrier frequency; pulse rates were (from top to bottom): 15, 20 (the standard rate) and 30 pulses s^–1.