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The acoustic basis for target discrimination by FM echolocating bats
1Department of Psychology, Brown University, Providence, Rhode Island 02912.
The Journal of the Acoustical Society of America
|October 1, 1989
Summary
Echolocating bats can discern prey shape using sonar, distinguishing mealworms from disks by analyzing echo waveforms. This acoustic perception relies on the target
Area of Science:
- Bioacoustics
- Animal Behavior
Background:
- Echolocating bats (Myotis lucifugus, Eptesicus fuscus) can discriminate airborne sonar targets during prey interception.
- Bats distinguish edible mealworms from inedible spheres, and Myotis can differentiate mealworms from disks of similar size.
Purpose of the Study:
- To investigate how bats perceive target shape using echolocation, particularly when spectral differences are minimal.
- To determine if bats can distinguish between targets based on their acoustic range profile.
Main Methods:
- Broadcasting ultrasonic impulses at mealworms, spheres, and disks.
- Recording and analyzing target echoes, including impulse echo waveforms and frequency response.
- Examining target transfer functions to understand acoustic properties.
Main Results:
- Echoes from disks and mealworms contain information about the target's range-axis profile (reflecting points/glints).
- This range profile is conveyed through impulse waveform structure and spectral notches/nulls.
- Bats can discriminate targets based on this acoustic range profile, even with similar echo amplitudes.
Conclusions:
- Bats perceive target shape through the acoustic representation of the range profile, not just spectral cues.
- This perception is crucial for accurate prey interception when targets are acoustically similar.