Horseshoe-like Structure Research Articles

Directional sensitivity of echolocation in the horseshoe bat,Rhinolophus ferrumequinum

The directionality of sound emission by a horseshoe bat (Rhinolophus ferrumequinum) has been determined for the constant frequency component of its orientation sounds. The bat was fixed in the center of an acoustic perimeter and the SPL of the orientation sounds measured with a scanning microphone at different angles compared with the SPL measured by another microphone located in the direction perpendicular to the plane of the horseshoe-like structure of the nose-leaf. The maximum SPL was always found in this direction which also corresponds to the flight direction of a bat in horizontal flight. Above and lateral to this direction the SPL decreases steadily with -6 dB-points at 24 ‡ above and 23 ‡ lateral. Below the flight direction we found a prominent side lobe with a -6 dB-point at 64 ‡.