Figure 2.

The effect of continuous noise stimuli on pulse emission rates. (A) Bats emitted pulses more frequently in the presence of continuous background noise than during intervening silent periods. The effect was similar whether recording from individuals or groups of bats. (B) The effect of stimulus duty cycle on the mean pulse emission rates of solitary bats. Error bars indicate standard deviation; asterisks indicate statistically significant differences from intervening silent periods (P < 0.01).