Fig. 4. The effect of varying pulse and pause duration on signal discrimination. The pulses for all stimuli were obtained from C. barbara calling song. (A) The pause duration was kept constant at 30 ms while the pulse duration was varied from 30 to 240 ms. All stimuli were equally effective (N=8). (B) The pause duration was varied between 7.5 and 120 ms while the pulse duration was fixed at 60 ms. Stimulus efficiency (measured as response latency to stimulus) decreased significantly with increasing pause duration. Values are means ± 95 % confidence intervals (N=5). DC, duty cycle (pulse duration/pulse period); NS, not significant.