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Experimental Studies on Target Detection, Evaluation and Interception by Echolocating Bats

Report Number: AMRL TR 65-172
Author: Webster, Frederic A.
Author: Brazier, Oliver G.
Corporate Author: Sensory Systems Lab Tucson Ariz
Laboratory: Aerospace Medical Research Laboratories
Date of Publication: 1965-11
Pages: 144
Contract: AF 33(615)-1142
Project: 7233 - Biological Information Handling Systems and Their Functional Analogs
Task: 723302 - Biological Servomechanisms
AD Number: AD0628055

The echolocation techniques of bats provide functioning models with useful attributes: versatility of application, ultra-miniaturization of components, and processing methods capable of dealing rapidly and reliably with complex echo indications despite the inherent slowness of unit neural components. Present experiments, carried out on captive bats trained to catch natural and artificial targets projected into their flight paths, have quantified certain basic measures of performance. Spheres as small as 1/16 inch diameter were detected and localized at two or more feet, with resulting interceptions being accomplished in 1/4 second. Final localization accuracies of 1 cubic centimeter were sometimes achieved, even when resolution of up to 16 nearby targets was required. Massive or complex clutter backgrounds tended to reduce interception performance at short target-to-clutter distances, but some interceptions were accurately completed during actual contact with natural twigs or goliage; or when pursuit paths had to be radically adapted to background configurations. Interception scores for food targets sometimes exceeded 99% while like-size negative targets of a different shape could be correctly discriminated roughly 95% of the time. Failure to make proper evaluation of trajectories tended to produce extensions of the terminal pursuit signal; but such modifications were not significantly incresed in most clutter situations.

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