Figure 1.

(a) The set-up with a linear horizontal array of three microphones and one microphone above the middle microphone. The microphones were separated by 1 m. The array was set with the horizontal microphones 30 cm over the water of a pond, where M. daubentonii hunted every night. The four microphones are marked with green numbers on the array and on the corresponding channels of the recording. We determined the (b) time-of-arrival differences (TOAD) of the sonar sounds between recording channels by cross-correlation.