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What We Do The Ocean Acoustics Department studies the propagation and scattering of sound in the ocean using theory and numerical modeling backed by ocean experiments. Research spans the frequency range from a few hertz to hundreds of kilohertz.We are acousticians who look at the ocean acoustics problem, and who collaborate with oceanographers to develop acoustical oceanography techniques; we are also oceanographers who use acoustics in our research. A Forward and an Inverse Problem The forward problem of ocean acoustic propagation is, "Given the ocean environment, what is the received signal?" The inverse problem is, "Given recorded acoustic data, what is the ocean environment?" The inverse problem may be nonlinear, non-unique, and sensitive to uncertainty in environmental properties and the details of the acoustic data.Enhancing U.S. Navy mid-frequency sonar (1–10 kHz) operation in shallow water involves theoretical and experimental efforts to better understand and model the physics of propagation and scattering. Ocean acoustics models are improved by including the influence of the rough ocean surface and variable seafloor. These models must balance fidelity against computational speed. Taking advantage of our knowledge of acoustic propagation in shallow water environments, we have begun to study the effects of mid-frequency sound on marine mammal communication, behavior, and health. This includes sound propagation research in the shallow waters of Puget Sound where bottom topography and sound speed variations in the water can significantly affect the sound levels incident on marine mammals as they move within their environment. To predict the capability of sonar to detect buried mines at shallow grazing angles, we are seeking a mechanistic understanding of scattering from, penetration into, and propagation within the seabed. Studies have shown that diffraction due to sand ripples is the main mechanism of penetration at shallow grazing angles and frequencies above 10 kHz. |
 Bob Odom, Chair Expertise
Educational Opportunities Graduate and undergraduate students can work under the tutelage of Ocean Acoustics Department investigators through their respective home UW academic colleges, including oceanography, engineering, and earth and space sciences. More >>Dr. Peter Dahl, for example, co-teaches Applied Acoustics (Mechanical Engineering 525), which introduces acoustics through its various applications and sub-fields, such as underwater sound (inlcuding sonar), medical ultrasound, and noise control and vibration. He also offers a Discovery Seminar Series for incoming UW freshmen students. In this General and Interdisciplinary Studies course (GIS 167) students consider the physics of sounds experienced every day such as music, the voice, the environmental sounds surrounding us, and less familiar sounds like medical ultrasound and underwater sound (sonar). Interested? Contact Peter Dahl. |
What's New?  Where and why large whales? Marine mammal scientists employ passive listening techniques to monitor large whales in the North Pacific. Hydrophone arrays record blue whale call patterns, which are then correlated with satellite data to show that sea surface temperature gradients or fronts often correspond to high zooplankton productivity and blue whale call locations. An ocean's temperature mapped by sound Multi-megameter acoustic propagation studies focus on the evolution, with distance, of the acoustic arrival pattern, and in particular the range and frequency dependence of the spatial and temporal coherence. Data analysis has produced a thermographic image of the North Pacific Ocean. More >> UW scientists to build largest underwater lab Scientists at the University of Washington plan to dig deeper into the mysteries of the ocean by building the world's largest underwater laboratory. More >> |