Fig. 3.

Changes in resting frequencies in response to BFN presentation. (A) Example of changes in vocal behavior in response to BFN presentation (condition 4). Spectrograms are plotted for a series of echolocation calls around BFN onset. The bat shows a shift in call frequency of 253 Hz in response to BFN presentation. (B) Shifts in call frequency in response to different BFN conditions (BFN amplitude: 100 dB SPL; playback attenuation: 30 dB) compared with no BFN stimulation; data averaged for all three bats. Medians: horizontal lines inside boxes; first and third quartile: upper and lower margins of boxes, respectively; 5% and 95% quantile: small horizontal bars above and below boxes, respectively. Dotted lines indicate the thresholds of the population effect size (±60 Hz). (C) Effects of different BFN intensities (C₁) and playback attenuations (C₂) on call frequency. Shifts in call frequency are shown in relation to shifts in response to BFN at 100 dB SPL in C₁, and relative to 30 dB playback attenuation in C₂). Data averaged for all three bats and all conditions. (C₁) Shift in call frequencies is slightly lower for weaker noise amplitudes (playback attenuation constant at 30 dB). (C₂) Stronger playback attenuation has no effect on shifts in call frequencies. (D) Changes of call frequency of the last 10 calls prior and the first 10 calls just after BFN presentation relative to the call frequency of the 10th call before noise onset. Data averaged for all three bats and noise conditions 2–6 (30 trials; medians with first and third quartile). First calls uttered after noise onset show a significant increase in call frequency (Kruskal–Wallis with post hoc signed-rank test).