Figure 1.

Schematic and example of acoustic stimuli. A: an ultrasound loudspeaker (S) and two microphones (M) were suspended 50 cm (lightest gray) from an object with artificial foliage suspended either +10 cm (middle gray) or +20 cm (black) behind the object. B: objects used in this study. Cylinder (blue), cube (maroon), small dipole (yellow), large dipole (orange), and small sphere (cyan). Details about object size and composition are found in Table 1. C: example echo spectrograms from the large dipole object. Synthetic calls with properties matched to average Eptesicus fuscus calls (purple arrow, 2 ms 100–20 kHz down sweep) were broadcast at objects in front of no clutter (top), +10 cm clutter behind object (middle), or +20 cm clutter behind object (bottom). Sonar sound broadcast and object echoes (orange) were recorded by two ultrasound microphones. Objects in front of clutter resulted in echoes with overlap between object echoes and clutter echoes (green).