Figure 5.

Set-up of the distance experiments. Schematic representation of the playback experiments (distance). All measurements are in cm. Two speakers (S) were located at the ends of a plank. A 66 cm long stick (dark-grey line) was used to obtain the correct distance of 1.32 cm between the female and the plank. Two nails (dark-grey circles) were used to obtain a triangle of 80° between the female and both speakers. The triangle was formed when the head of both nails were in line with the female.