Passive bottom reflection-loss estimation using ship noise and a vertical line array.

Area of Science:

• Oceanography
• Marine acoustics
• Seismic signal processing

Background:

• Passive acoustic methods traditionally use natural ocean surface noise for seafloor characterization.
• Estimating seafloor properties is crucial for various marine applications, including geological surveys and underwater navigation.
• Existing techniques rely on the characteristics of ambient noise fields recorded by hydrophone arrays.

Purpose of the Study:

• To adapt an existing passive acoustic technique for bottom-loss estimation.
• To utilize anthropogenic noise, specifically ship noise, as an alternative source for passive acoustic measurements.
• To investigate the feasibility of using ship noise for characterizing seafloor acoustic properties.

Main Methods:

• Adapting a beamforming technique originally designed for natural marine surface noise.
• Processing noise fields recorded by a vertical line array of hydrophones.
• Ensuring a wide range of ship positions relative to the array to cover diverse steering angles, ideally passing directly overhead.

Main Results:

• Demonstrated that ship noise can be processed to exhibit features similar to natural surface noise fields.
• Validated the adapted methodology through simulations.
• Successfully applied the technique to field experiment data collected offshore of San Diego in 2009.

Conclusions:

• Ship noise can be effectively utilized for passive acoustic estimation of seafloor properties.
• The adapted beamforming technique provides a viable alternative to using natural noise sources.
• This method offers flexibility in acoustic surveying by leveraging available anthropogenic noise.