Department Lead |
|
 |
|
Todd Hefner
Senior Principal Physicist |
|

|
|

|
|
What We Do |
|
|
Expertise |
|
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.
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
|
Fruit Bats Use Tongue to Point Sonar Beams |
|
|
SAMS: The Sediment Acoustic-speed Measurement System |
|
|
First Research Deployment for IVAR |
|
|
|
|
|
|
Projects |
All |
|
Media Coverage |
All |
|
Publications |
All |
 |
|
Understanding Echoes: A Keynote Lecture at the Acoustical Society of America Meeting
Wu-Jung Lee
23 May 2022
|

|
 |
|
MuST Multi-Sensor Towbody
Kevin Williams, Timothy Marston, Tim McGinnis, Ben Brand, Nick Michel-Hart
7 March 2022
|

|
 |
|
APL-UW Internship Program: Applied Research Experience for NROTC Students
Aubrey Espana, Kevin Williams
6 October 2021
|

|
|
|
 |
|
NTSB locates wreckage of floatplane that crashed into Puget Sound
KING5 News
12 September 2022
|

|
 |
|
This year's Arctic Report Card is filled with predictable trends and new obstacles
Anchorage Daily News
Ned Rozell
18 December 2021
|

|
 |
|
Ocean Jazz
The Loh Down on Science (Podcast)
Ted Yoo
2 July 2021
|

|
|
|
 |
|
Head-related transfer function predictions reveal dominant sound propagation mechanisms to the dolphin ears
Cheong, Y.J., A. Ruesch, M.D. Schalles, J.M. Kainerstorfer, Shinn-Cunningham, B., and W.-J. Lee
8 July 2025
|

|
 |
|
Movement trajectories reflect active information acquisition by an echolocating porpoise in a target discrimination task
Lee, W.-J., M. Ladegaard, M.D. Schalles, J.R. Buck, K. Beedholm, P.T. Madsen, and P.L. Tyack
7 July 2025
|

|
 |
|
Observations of mid-frequency sound propagation on the Washington continental shelf with a subsurface duct
Tang, D., B.T. Hefner, G. Xu, E.I. Thorsos, R.R. Harcourt, J.B. Mickett, and K.R. Prakash
18 June 2025
|

|
|