Fig. 2.

Experimental setup for auditory neurophysiology in the SC of the bat showing the arrangement for manipulating the direction and distance of an auditory stimulus during extracellular recording. The bat was placed in the acoustic booth with its head at the edge of the table at a distance of 40 cm from the speaker hoop. All 15 loudspeakers, arranged ∼13° apart in a hemifield, were positioned at an equal distance from the bat and showed similar frequency response profiles (see Materials and Methods). Azimuthal sensitivity was studied by recording neural responses to sounds broadcast through each of the loudspeakers. The speaker hoop was rotated to move the sound source along the vertical axis to test sensitivity to changes in elevation. Target range was simulated using pairs of sounds (P and E) separated by particular delays.