At the meeting, Moss will summarize the bat's adaptive vocal behavior as it engages in complex spatial tasks. Her team recorded the bat's 3D flight path with high-speed stereo infrared video, and recorded its sonar signals with a microphone array that permitted them to reconstruct the emission. They found that the big brown bat (Eptesicus fuscus) "points" its sonar beam in different directions to inspect objects in its environment. The bat's beam is sufficiently wide (within a 60-90 degree cone) to enable it to gather information about closely spaced objects (a complex environment) simply by directing its beam in the general direction of those objects. Instead, the bat points the center of its beam sequentially at these objects.
According to Moss, this suggests that the bat is carefully analyzing acoustic information separately from closely spaced objects. The bat also modifies the duration of its calls to avoid overlap between vocalizations and echoes. When the bat encounters objects that are at a close distance, it produces shorter sonar calls than when it encounters objects that are further away. In Moss's latest research, the bat encountered an obstacle that was closer to it than an edible food reward, and made adjustments in the duration of its calls, indicating to the researchers whether it was paying attention to the near or the distant objects.
Paper 2pABa1, "The echolocating bat controls the direction and distance of its acoustic gaze." will be presented at 2:20 p.m. on Tuesday, July 1 in room 342B.
7) HOW BATS COMPENSATE FOR RANGING ERRORS
Echolocating bats obtain 3D images of their surroundings in complete darkness by emitting sonar signals and evaluating returning echoes. When flying close to objects, bats risk collision and therefore depend on the accuracy of those auditory images -- particularly in the perceived distanc
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American Institute of Physics