Range estimation of cetaceans with compact volumetric arrays

Area of Science:

• Marine Biology
• Acoustics
• Oceanography

Background:

• Passive acoustic monitoring is crucial for detecting marine mammals and studying their behavior.
• Existing methods face challenges in precise localization and ranging.

Purpose of the Study:

• To introduce and evaluate a novel compact passive acoustic monitor (CPAM) for marine mammal detection.
• To assess the CPAM's capability in estimating sound direction and range to acoustically active animals.

Main Methods:

• The CPAM utilizes three arrays of two hydrophones in a fixed 3D configuration, towed at depths over 100m.
• It employs two ranging methods: basic geometry (constant sound speed) and ray-tracing (variable sound speed profiles).
• Both methods integrate sound arrival angles and surface reflection delays for real-time analysis.

Main Results:

• The CPAM's volumetric configuration enables 3D direction vector estimation of incoming sounds.
• Under specific geometric conditions, the system can estimate range to echolocating animals.
• Ray-tracing methods show promise for integrating real sound speed profiles for enhanced accuracy.

Conclusions:

• The CPAM offers advanced capabilities for passive acoustic monitoring of whales and dolphins.
• The ray-tracing approach is recommended for its ability to incorporate real-world sound speed variations.
• This technology can significantly advance underwater acoustic behavior studies.