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Acoustic reflectivity of a dolphin
1Hawaii Institute of Marine Biology, University of Hawaii, Kailua 96734, USA.
The Journal of the Acoustical Society of America
|June 1, 1996
Summary
This study measured the acoustic target strength of Atlantic bottlenosed dolphins. Findings reveal how dolphin body shape and internal structures, like lungs, influence sound reflection across various frequencies and angles.
Area of Science:
- Marine biology
- Acoustics
- Bioacoustics
Background:
- Understanding marine mammal acoustics is crucial for sonar applications and conservation.
- Dolphin acoustic properties are influenced by their physiology and environment.
Purpose of the Study:
- To quantify the acoustic target strength of an Atlantic bottlenosed dolphin.
- To investigate how frequency, aspect angle, and body region affect acoustic reflectivity.
Main Methods:
- Backscatter measurements were performed on a stationary dolphin under controlled conditions.
- Target strength was analyzed as a function of frequency (23-80 kHz) and polar angle.
- Relative reflective strength of different body portions was assessed.
Main Results:
- Mean target strength decreased with increasing frequency from 23-45 kHz, then showed a peak at 66 kHz.
- Maximum target strength occurred at the broadside aspect, significantly higher than the tail aspect.
- The area between dorsal and pectoral fins, containing the lungs, was the primary reflector of acoustic energy.
Conclusions:
- Dolphin acoustic target strength is frequency-dependent and varies with viewing angle.
- The dorsal region, particularly near the lungs, is a key area for acoustic reflection in dolphins.
- These findings have implications for passive acoustic monitoring and sonar detection of marine mammals.