Sai Geetha Seri’s PhD Proposal Review

“Advancing Passive Ocean Acoustic Waveguide Remote Sensing for Detection of Fish Sounds, Seismo-Acoustic Airgun Signals, and Marine Mammal Vocalizations including Instrumentation Enhancements”

Committee:

Prof Purnima Ratilal Makris (Advisor)
Prof Josep M Jornet
Dr Nils Olav Handegard

Abstract:

Underwater passive acoustic monitoring is important for understanding the marine environment, since many ocean entities produce sound that can travel long ranges especially at low frequencies. For instance, sound plays a vital role in the communication, navigation, and behavior of many marine biological organisms. Human activities in the ocean, such as shipping, offshore piling, and energy prospecting, generate a wide range and levels of sound. Natural environmental processes, such as the passage of a hurricane and offshore seismicity are sources of underwater sound. In this thesis, the instantaneous wide-area Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) technology implemented with a coherent hydrophone array is developed further and enhanced in a number of ways. First, the automatic detection and analysis of man-made seismo-acoustic airgun signals employed in offshore geophysical and energy exploration surveys is investigated. Next, the POAWRS technique is applied successfully for the first time toward the analysis and identification of sounds from some oceanic fish species in the wild using an eight-element prototype hydrophone array. Probability of Detection (PoD) regions are quantified separately for both the seismo-acoustic signals and fish sounds to provide an understanding of the horizontal spatial propagation extent of the acoustic signals from these sources. Finally, we demonstrate significant enhancements in monitoring marine mammal sounds to include real-time capability and over a wider frequency range via a new in-house developed and fabricated 160-element coherent hydrophone array system. Here, data from three distinct receiver array systems are analyzed, presenting a technological evolution in the sensor systems utilized to implement and advance the POAWRS approach for ocean sensing. Development and integration of data acquisition approaches for both acoustic and non-acoustic sensors contained in the in-house developed array are discussed, including design challenges and solutions.