Histograms of the distribution of acoustic impulses. The horizontal axis shows time from the start of recording, in sec; the vertical axis shows the number of impulses in each recording channel. The quantization step was 20 msec. Vertical lines indicate the points of starting (0.8 sec) and ending (1.4 sec) the visual stimulus imitating the movement of an obstacle to the left (L), right (R) relative to the insect, and directly towards the insect (F). The diagram below shows changes in the calculated distance (et) between the obstacle and the insect. Each histogram was constructed using the results of 21 stimulus presentations.