Year: 1975
Type: conference-abstract
Abstract: Microchiropteran bats, many cetaceans, and several species of birds have independently evolved active sonar for acoustic imaging of their surroundings. Echologcating birds emit acoustic clicks at 1 to 10 kHz for orientation. Echolocation enables birds to detect wires as small as 1.0 mm in diameter, providing a perceptual acuity appropriate for obstacle avoidance and navigation. Echolocating bats comprise about 20% of all mammalian species and exhibit sophisticated adaptations of hearing which led to early success and diversity. Two classes of bat orientation signals are used for different purposes: FM sounds for target description and localization, and CF sounds for improving target detection and determining target velocity from echo Doppler shifts. These signals occur in several patterns (FM-CF, CF-FM, FM) that relate to acoustic environments. Using broad bandwidths and high frequencies (20 to 150 kHz) to exploit the superb ultrasonic hearing of mammals, bats can resolve wires as small as 0.1 mm and can perceive fine target features. Bat echolocation appears primarily adapted to acoustic constraints influencing target detection (long ranges or small targets). Cetaceans use different kinds of orientation signals; short clicks of broad bandwidth and high frequencies (10–150 kHz) being best known. These clicks, at least, seem adapted for fine resolution rather than long-range detection in the highly reverberant underwater environment. Difficulties in observing behavior and conducting experiments limit available data on cetaceans. These data indicate that fine target resolution is possible.
DOI: 10.1121/1.2002000
Author: J. A. Simmons
Institution: Washington University in St. Louis
Language: English
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2052223934