Extracting the time domain Green's function from ocean ambient noise using acoustic vector sensors

Area of Science:

• Ocean acoustics
• Signal processing
• Geophysics

Background:

• Recovering the two-point time-domain Green's function (TDGF) is crucial for understanding multipath time delays between sensors.
• Traditional methods rely on correlating noise fields, which can be time-consuming.
• Ambient ocean noise serves as a viable source for passive acoustic sensing.

Purpose of the Study:

• To present a novel technique for extracting the TDGF from ambient ocean noise.
• To utilize acoustic vector sensors for enhanced TDGF retrieval.
• To compare the efficiency of acoustic vector sensors against traditional hydrophones.

Main Methods:

• Correlating noise fields measured by two acoustic vector sensors.
• Employing ambient ocean noise as the signal source.
• Analyzing vertical velocity data for TDGF extraction.

Main Results:

• Acoustic vector sensors significantly reduce the required averaging time for TDGF extraction.
• Direct and bottom bounce arrivals were successfully extracted using only 1 minute of vertical velocity data.
• Bottom bounce arrivals were not extracted even with 10 minutes of sound pressure data from hydrophones.

Conclusions:

• Acoustic vector sensors offer a more efficient method for recovering TDGF from ambient ocean noise.
• This technique accelerates multipath analysis in underwater acoustic environments.
• The findings demonstrate a substantial improvement over traditional sound pressure-based methods.