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.
Acoustic propagation and scattering from volume heterogeneities and surface roughness
- Undersea acoustic communications
- Remote sensing of the environment
- Acoustical oceanography
- Scattering from objects deployed in the ocean
- Ambient noise in air and underwater environments
- Measurement and control of underwater industrial noise
- Arctic acoustics
Philip Marston, WSU
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)
Mitigating Supersonic Underwater Noise
Construction projects in marine environments often involve impact pile driving. Collaborative research shows that a double-walled steel tube placed around the pile can shield the underwater environment from much of the acoustic energy. More >>
TREX13: Target and Reverberation EXperiment 2013
This ocean acoustics experiment will be staged in the Gulf of Mexico near Panama City, FL, to measure mid-frequency reverberation in a shallow water environment and to detect and classify unexploded ordnance and mine-like targets on the seafloor using synthetic aperture sonar. More >>
In the News
Are Spitsbergen whales making a comeback?
KUOW Radio, "The Conversation", Ross Reynolds
9 Aug 2012
Commercial whaling almost drove Spitsbergen whales to extinction. Since the 1970s sightings have been few and far between. Kate Stafford and her colleagues are using hydrophones to observe these whales year-round.
Capturing the winter songs of rare whales
New York Times, Kelly Slivka
7 Aug 2012
Between Greenland and the northern island of Spitsbergen, Norway, in the blackness of the Arctic winter, a group of rare whales sing. Kate Stafford, a bowhead researcher, is the lead author of a new paper in the journal Endangered Species Research that paper describes the variegated calls of Spitsbergen's bowheads, captured on underwater acoustic recorders by Dr. Stafford and her colleagues.
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.
De Robertis, A., C.D. Wilson, S.R. Furnish, and P.H. Dahl, "Underwater radiated noise measurements of a noise-reduced fisheries research vessel," ICES J. Mar. Sci., 70, 480-484, doi:10.1093/icesjms/fss172, 2013.
1 Mar 2013, Link
Stafford, K.M., S.R. Okkonen, and J.T. Clarke, "Correlation of a strong Alaska Coastal Current with the presence of beluga whales Delphinapterus leucas near Barrow, Alaska," Mar. Ecol. Prog. Ser., 474, 287-297, doi:10.3354/meps10076, 2013.
31 Jan 2013, Link
Udovydchenkov, I.A. R.A. Stephen, T.F. Duda, S. Thompson Bolmer, P.F. Worcester, M.A. Dzieciuch, J.A. Mercer, R.K. Andrew, and B.M. Howe, "Bottom interacting sound at 50 km range in a deep ocean environment," J. Acoust. Soc. Am., 132, 2224-2231, doi:10.1121/1.4747617, 2012.
1 Oct 2012, Link
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.