Acoustics

Professor 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

Acoustic 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 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)

Infrasound 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 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.

LCDR Tsu Wei Tan (TW) | Email: ttan1@nps.edu
LCDR Tan works on applications of the time-warping signal processing technique in underwater noise inter-ferometry for passive acoustic remote sensing of the ocean, including the geoacoustic properties of the seabed.

LT Rodney Thatcher | Email: rodney.thatcher@navy.mil
LT Thatcher studied acoustic nonreciprocity induced by oceanic currents and develops a technique for retrieving the current velocity profile from measurements of ambient and shipping noise.

ENS Ryan Mcmullin | Email: ryan.mcmullian@navy.mil
ENS Mcmullin investigated 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 and ENS Richard Wyman | Email: richard.wyman@nps.edu
Advised by Prof. Denardo, ENS Mcmellon and ENS Wyman conducted proof-of-principle experiments for a recent theory of passive, broadband noise suppression by Godin and Baynes.

MAJ Dexter Tan (SN) | Email: dexter.tan.sn@nps.edu
MAJ Tan investigated applications of acoustic time-reversal mirrors to passive acoustic remote sensing of the coastal ocean.

LT Yi-fan Shen (TW) | Email: yifan.shen.tw@nps.edu
LT Shen studied the ways to decrease the averaging time that is required in noise interferometry to retrieve the empirical Green’s functions for passive acoustic characterization of the ocean.

LCDR Alexandre Geddes Lemos Guarino (BR) | Email: alexandre.guarino.br@nps.edu
LCDR Guarino investigates application of vector sensors to acoustic characterization of the seabed.

CDR Matthew Walters | Email: mattew.walters@nps.edu
CDR Walters prepares and will conduct a long-term, deep-water experiment on passive acoustic remote sensing in the Atlantic Ocean.

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

• Godin O. A., Zabotin N. A., and Zabotina L., Atmospheric resonances and their coupling to vibrations of the ground and waves in the ocean, Earth, Planets and Space, 72, Art. 125, 125-1–125-19 (2020)

• Godin O. A., Deal T. J., and Dong H., Physics-based characterization of soft marine sediments using vector sensors, J. Acoust. Soc. Am. 149, 49–61 (2021)

• Katsnelson B. G., Godin O. A., and Zhang Q., Observations of acoustic noise bursts accompanying nonlinear internal gravity waves on a continental shelf off New Jersey, J. Acoust. Soc. Am., 149, 1609–1622 (2021)

• Godin O. A. Shear waves and sound attenuation in underwater waveguides, J. Acoust. Soc. Am., 149, 3586–3598 (2021)

• Tan T. W. and Godin O. A., Passive acoustic characterization of sub-seasonal sound speed variations in a coastal ocean, J. Acoust. Soc. Am., 150, 2717–2737 (2021)

• Godin O. A., Contributions of gravity waves in the ocean to T-phase excitation by earthquakes, J. Acoust. Soc. Am., 150, 3999–4017 (2021)

• Application of time reversal to passive acoustic remote sensing of the ocean, Acoustical Physics, 63, 309–320 (2017)

  Godin O. A., Katsnelson B. G., Qin J., Brown M. G., Zabotin N. A., and Zang X.
• Acoustic noise interferometry in a time-dependent coastal ocean, Journal of the Acoustical Society of America, 143, 595–604 (2018)
  Godin O. A.
• Passive, broadband suppression of radiation of low-frequency sound, Journal of the Acoustical Society of America, 143, EL67–EL73 (2018)
  Godin O. A. and Baynes A. B.
• Normal mode dispersion and time warping in the coastal ocean, Journal of the Acoustical Society of America, 146, EL205–EL211 (2019)
  Godin O. A., Katsnelson B., and Tan T. W.
• Characterizing the seabed in the Straits of Florida by using acoustic noise interferometry and time warping, Journal of the Acoustical Society of America, 146, 2321–2334 (2019)
  Tan T. W., Godin O. A., Brown M. G., and Zabotin N. A.