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What We Do The Acoustics Department studies the propagation and scattering of sound. Historically our primary focus has been the ocean and on structures in the ocean using theory and numerical modeling backed by ocean experiments. In the next ten years we plan to strengthen our non-ocean related research efforts.Our research spans the frequency range from a few hertz to hundreds of kilohertz. We seek to understand and quantitatively predict propagation and scattering (the ‘forward’ problem). These predictions require detailed knowledge of the environment and the material properties of targets. To measure the ocean environment, we collaborate with physical, biological and geophysical oceanographers. Those same collaborations are essential to our development of acoustical oceanography techniques (the ‘inverse’ problem). A forward problem in environmental acoustics asks, "Given the environment, what is the received signal?" High fidelity forward models then allow us to address the inverse problem, "Given recorded acoustic data, what is the environment?" Solving the forward problem requires a combination of physical understanding, theoretical development, and analytic and numerical modeling. The inverse problem offers many challenges as well, since it may be nonlinear, non-unique, and sensitive to uncertainty in environmental properties and the details of the acoustic data. Expertise
Affiliate Members Philip Marston, WSU |
What's New? 
Acoustic Color of Mines & Mine-Like Objects Kevin Williams, Steven Kargl, Aubrey Espana (PDF 3 MB) 
Acoustic Detection of Unexploded Ordnance Aubrey España's presentation at the 31 Oct 2011 Acoustical Society of America's Webcast on Discoveries in Acoustics (Quicktime Movie, 64 MB)Acoustic Intensity Properties in an Ocean Waveguide David Dall-Osto, Peter H. Dahl (PPT 2 MB) Modeling a Spiral Wave Front Source in an Ocean Environment Brian T. Hefner, Benjamin R. Dzikowicz (PDF 15.6 MB) Pressure-particle Velocity Coherence David Dall-Osto, Peter H. Dahl (PPT 3 MB) Physics-Based Inversion of High-Frequency Multibeam Sonar Data Darrell Jackson and Brian T. Hefner (PDF 250 Kb) 
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 >> |
In the News Conscripting terahertz sensors Photonics Spectra, Lynn Savage 1 Apr 2012 Teraherz waves are useful to security agents and military personnel alike for revealing concealed weapons, chemical explosives and biological agents. A technique developed by APL-UW researchers permits a better spectral signal-to-noise ratio from targets, even given very rough surface equivalents and only a few disjoint terahertz measurements of the target particles. The researchers report, however, that more work is needed to nail down the minimum number of measurements needed for certainty. Scientific American, Charles Q. Choi 1 Sep 2011 Light curtains of air may protect fish from the din of humans. The bubbles alone may not fully solve the problem. They may dampen sound traveling through the water from above, but about 10 percent of the noise from underwater pile driving would still get transmitted up from the seabed, says acoustician Peter Dahl of the University of Washington. Under the ice, sounds of spring The New York Times 17 May 2011 Kate Stafford, an oceanographer at APL-UW, writes from Alaska for the New York Times Scientist at Work blog, where she is participating in a visual census of bowhead whales. Recent Papers Tang, D., and B.T. Hefner, "Modeling interface roughness scattering in a layered seabed for normal-incident chirp sonar signals," J. Acoust. Soc. Am., 131, EL302-EL308, doi:10.1121/1.3690962, 2012. 1 Apr 2012, Link Dall'Osto, D.R., P.H. Dahl, and J.W. Choi, "Properties of the acoustic intensity vector field in a shallow water waveguide," J. Acoust. Soc. Am., 131, doi:10.1121/1.3682063, 2023-2035, 2012. 1 Mar 2012, Link Hefner, B.T., and B.R. Dzikowicz, "Acoustic propagation from a spiral wave front source in an ocean environment," J. Acoust. Soc. Am., 131, 1978-1986, doi:10.1121/1.3682045, 2012. 1 Mar 2012, Link Educational Opportunities Graduate and undergraduate students can work under the tutelage of the Acoustics Department investigators through their respective home UW academic colleges, including oceanography, engineering, and earth and space sciences. More >>Dr. Peter Dahl, for example, 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. |
