Acoustic Surface Wave Measurements on Live Bottlenose Dolphins.
Abstract
The surface wave velocity and absorption constant were determined on live bottlenose dolphins as a function of position, propagation direction, and frequency. A progressive wave was propagated on the outer skin of a dolphin by an electromagnetic shaker driven by a noise source. Two miniature accelerometers were attached to the skin at a distance of 3.2 cm apart. The output signals from the accelerometers were analyzed by a dual channel Fast Fourier Transform Spectrum Analyzer. The data acquisition was further automated by a minicomputer. The surface wave velocities were the highest below the dorsal fin area and the lowest at an area around the posterior insertion of the pectoral fin. Generally, the velocity and absorption constant were independent of the propagation direction (anterior, posterior, dorsal, and ventral) except near the dorsal fin. Over most of the regions measured, the surface wave velocity ranged from 4 to 14 m/sec over the frequency range of 100 to 1000 Hz. The attenuation alpha (dB/m) was assumed to be a alpha = Af where A is the absorption constant and f is the frequency. The absorption constant was the highest around a line at the posterior insertion of the pectoral fin, 1.5 dB sec/m, and the lowest just below the dorsal fin, 0.5 dB sec/m.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1983
- Accession Number
- ADA146623
Entities
Organizations
- Naval Ordnance Laboratory