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Acoustics


Professor GodinProfessor Oleg A. Godin, PhD, DSc

Professor of Physics and Chair of the Engineering Acoustics Academic Committee
Phone: (831) 656-2982  | Email: oagodin@nps.edu

Dr. Godin’s current research interests include theory of wave propagation and diffraction in inhomogeneous and non-stationary media; underwater acoustics; ocean remote sensing; and noise interferometry. He is an author of 5 books, including a two-volume monograph Acoustics of Layered Media (Springer, New York etc., 1990–1992 and 1998–1999) (with L. M. Brekhovskikh) and 150 peer-reviewed journal papers. He is a Fellow of the Acoustical Society of America and a member of the American Geophysical Union and European Geophysical Union.. 


Current Research Programs

placeholderAcoustic Noise Interferometry and Passive Ocean Remote Sensing

This project investigates a new, low-cost and environmentally friendly passive approach to remote sensing of the ocean interior, which takes advantage of ambient underwater acoustic fields. Noise cross-correlations between pairs of hydrophones are used as a probing signal to measure the sound speed (water temperature) and current velocity fields in the water column and ocean bottom properties.

 

Sponsor: National Science Foundation. Collaborations with University of Miami, University of Colorado, and Haifa University.

 

 


Applications of Time-Reversal Mirror in Acoustic Remote SensingApplications of Time-Reversal Mirror in Acoustic Remote Sensing

We have demonstrated experimentally that a time-reversal mirror can be realized in a coastal ocean by recording ambient and shipping noise with just two hydrophones separated by a distance that is as large as 100 ocean depths. This project investigates stability of the focus of the backpropagated field in a dynamic ocean and sensitivity of the position and strength of the focus to variations of environmental parameters. The goal of the project is to develop a time-reversal-based., robust technique to measure geoacoustic parameters of the seafloor.


Sponsor: National Science Foundation. Collaborations with University of Miami, Haifa University, and École Navale (Brest)

 


 

infrasoundInfrasound and Acoustic-Gravity waves

 

The project Resonance properties of the Ross Ice Shelf, Antarctica, as a factor in regional wave interaction between ocean and atmosphere aims to explain observations of ionospheric manifestations of waves in the ocean and its ice cover, quantify coupling between long waves in the ocean and atmosphere, and access remote sensing implications of the coupling.
 

Sponsor: National Science Foundation. Collaborations with University of Colorado, Woods Hole Oceanographic Institution, and Scripps Institute of Oceanography

 

 


Rayleigh scattering of sound in underwater waveguidesRayleigh scattering of sound in underwater waveguides

 

This project investigates scattering of low-frequency sound by objects in oceanic waveguides. The long-term goal of this research is to develop effective techniques for characterizing compact scatterers and retrieving quantitative information about their structure and physical parameters from low-frequency acoustic fields, and to investigate and quantify effects of proximity of scatterers to the waveguide’s boundaries and to each other on sound scattering in the ocean. Applications of the results obtained in the course of this project include

  • Characterizing, correcting, and exploiting distortions of the ambient acoustic field by sensor platform to improve target detection with mounted hydrophones and vector sensors,
  • Development of a passive technique for broadband suppression of unwanted low-frequency acoustic radiation, such as propeller noise.

 

Sponsor: ONR Ocean Acoustics Program. Collaborations with NUWC Newport and Prof. Bruce Denardo.


Research Team

 

LCDR Alexander B. Baynes | Email: alexander.b.baynes@navy.mil

LCDR Baynes develops a numerically efficient and intuitive model of multiple scattering of low-frequency sound in oceanic waveguides.
 

LT Rodney Thatcher | Email: rodney.thatcher@nps.edu

LT Thatcher studies acoustic nonreciprocity induced by oceanic currents and develops a technique for retrieving the current velocity profile from measurements of ambient and shipping noise.


LCDR Tsu Wei Tan | Email: ttan1@nps.edu

LCDR Tan works on applications of the time-warping signal processing technique in underwater noise interferometry for passive acoustic remote sensing of the ocean, including the geoacoustic properties of the seabed.


ENS Ryan Mcmullin | Email: ryan.mcmullin@nps.edu

ENS Mcmullin investigates applications of passive acoustic time-reversal mirrors to quantitative characterization of the propagation environment and detection of quiet targets in the coastal ocean.


ENS Evan J. Mcmellon | Email: evan.mcmellon@nps.edu

Advised by Prof. Denardo, ENS Mcmellon develops a proof-of-principle experiment for a recent theory of passive, broadband noise suppression by Godin and Baynes.


Available Thesis Topics

  • Noise interferometry: Order emerging from chaos

  • Infrasound in the ocean and atmosphere

  • Acoustic time-reversal mirror

  • Acoustic remote sensing of the ocean

  • Rayleigh scattering of acoustic and electromagnetic waves

  • Passive suppression of radiation of low-frequency sound

  • Fidelity of low-frequency acoustic measurements by mounted sensors

  • Acoustic-gravity waves: From the ocean and ice shelves to space

 

Recent Publications


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