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Propagation of beluga echolocation signals
1Naval Ocean Systems Center, Kailua, Hawaii 96734.
The Journal of the Acoustical Society of America
|September 1, 1987
Summary
Beluga whales (Delphinapterus leucas) use distinct echolocation signal modes for target detection. These modes vary in click intervals and beam patterns, influencing acoustic near- and far-field propagation.
Area of Science:
- Marine biology
- Bioacoustics
- Animal behavior
Background:
- Beluga whales (Delphinapterus leucas) utilize high-frequency echolocation for navigation and foraging.
- Understanding echolocation signal propagation is crucial for interpreting marine mammal sensory capabilities.
Purpose of the Study:
- To measure the propagation characteristics of beluga echolocation signals during a target detection task.
- To identify different signal modes and their acoustic properties.
Main Methods:
- Hydrophone arrays were used to measure vertical and horizontal transmission beam patterns.
- The acoustic near- and far-field transition region was determined.
- Beluga whales were trained to station for precise acoustic measurements.
Main Results:
- Three distinct echolocation signal modes were identified based on click intervals relative to two-way transit time.
- Mode 1 signals (long intervals) exhibited narrow beamwidths (approx. 6.5 degrees) directed slightly upward.
- The near- to far-field transition occurred between 0.64-0.75 m from the mouth.
Conclusions:
- Beluga echolocation signals exhibit complex propagation patterns.
- Signal characteristics are adapted for effective target detection in different acoustic conditions.
- The findings provide insights into the acoustic behavior of beluga whales.