Fig. 4.

Phonotaxis to interdigitated (10 ms onset delay) sources. Two synthetic sound sources broadcast with a 10-ms onset delay to produce interdigitated chirps (Inset). (A) Average walking response of flies (n = 10 flies) to sources separated by 90°. (B) Average walking response of flies to sources separated by 180° (n = 10 flies). Square symbols and horizontal/vertical projections from symbols indicate the mean and confidence intervals of the location of flies at 0.03-s intervals. Filled symbols indicate walking responses to forward (A) or left (B) leading sound sources while open symbols indicate walking response to lateral or right leading sound sources. Flies responded to interdigitated sources by directing phonotaxis to a phantom source location between the broadcasting speakers (45° heading in 90° condition, 0° heading in 180° condition) but with a slight bias toward leading sources.