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Peter Dahl

Senior Principal Engineer

Professor, Mechanical Engineering

Email

dahl@apl.washington.edu

Phone

206-543-2667

Research Interests

Underwater Acoustics, Acoustic Remote Sensing

Biosketch

Dr. Dahl is a Senior Principal Engineer in the Acoustics Department and a Professor in the University of Washington's Department of Mechanical Engineering. Professor Dahl's research is in areas of acoustics with primary focus on underwater sound. Examples of his research include underwater acoustic remote sensing, the acoustics of underwater explosions, acoustic scattering and reflection from the sea surface and sea bed, vector acoustics, underwater ambient noise and methods to reduce underwater industrial noise.

He has conducted several ocean-going experiments involving underwater acoustics, including the Asian Seas International Acoustics Experiment (ASIAEX), sponsored by the U.S. Office of Naval Research, in the East China Sea involving the U.S., China and Korea and for which he was U.S. chief scientist.

Professor Dahl is a Fellow of the Acoustical Society of America, has served as the chair of its technical committee on underwater acoustics (2002–2005), on its Executive Council (2008–2011), and has recently completed service as Vice President of the Acoustical Society of America.

Department Affiliation

Acoustics

Education

B.S., University of Washington - Seattle, 1976

M.S. Ocean and Fishery Sciences, University of Washington - Seattle, 1982

Ph.D. Ocean Engineering, MIT, 1989

Publications

2000-present and while at APL-UW

Physical effects of sound exposure from underwater explosions on Pacific mackerel (Scomber japonicus): Effects on non-auditory tissues

Jenkins, A.K., P.H. Dahl, S.E. Kotecki, V. Bowman, B. Casper, C. Boerger, and A.N. Popper, "Physical effects of sound exposure from underwater explosions on Pacific mackerel (Scomber japonicus): Effects on non-auditory tissues," J. Acoust. Soc. Am., 151, 3947-3956, doi:10.1121/10.0011587, 2022.

More Info

1 Jun 2022

Underwater explosions from activities such as construction, demolition, and military activities can damage non-auditory tissues in fishes. To better understand these effects, Pacific mackerel (Scomber japonicus) were placed in mid-depth cages with water depth of approximately 19.5 m and exposed at distances of 21 to 807 m to a single mid-depth detonation of C4 explosive (6.2 kg net explosive weight). Following exposure, potential correlations between blast acoustics and observed physical effects were examined. Primary effects were damage to the swim bladder and kidney that exceeded control levels at ≤333 m from the explosion [peak sound pressure level 226 dB re 1 μPa, sound exposure level (SEL) 196 dB re 1 μPa2 s, pressure impulse 98 Pa s]. A proportion of fish were dead upon retrieval at 26–40 min post exposure in 6 of 12 cages located ≤157 m from the explosion. All fish that died within this period suffered severe injuries, especially swim bladder and kidney rupture. Logistic regression models demonstrated that fish size or mass was not important in determining susceptibility to injury and that peak pressure and SEL were better predictors of injury than was pressure impulse.

Vector acoustic and polarization properties of underwater ship noise

Dahl, P.H., and J. Bonnel, "Vector acoustic and polarization properties of underwater ship noise," J. Acoust. Soc. Am., 151, 3818-3827, doi:10.1121/10.0011410, 2022.

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1 Jun 2022

Vector acoustic field properties measured during the 2017 Seabed Characterization Experiment (SBCEX17) are presented. The measurements were made using the Intensity Vector Autonomous Recorder (IVAR) that records acoustic pressure and acceleration from which acoustic velocity is obtained. Potential and kinetic energies of underwater noise from two ship sources, computed in decidecimal bands centered between 25–630 Hz, are equal within calibration uncertainty of ±1.5 dB, representing a practical result towards the inference of kinematic properties from pressure-only measurements. Bivariate signals limited to two acoustic velocity components are placed in the context of the Stokes framework to describe polarization properties, such as the degree of polarization, which represents a statistical measure of the dispersion of the polarization properties. A bivariate signal composed of vertical and radial velocity components within a narrow frequency band centered at 63 Hz representing different measures of circularity and degree of polarization is examined in detail, which clearly demonstrates properties of bivariate signal trajectory. An examination of the bivariate signal composed of the two horizontal components of velocity within decidecimal bands centered at 63 Hz and 250 Hz demonstrates the importance of the degree of polarization in bearing estimation of moving sources.

The detection of seismicity on icy ocean worlds by single-station and small-aperture seismometer arrays

Marusiak, A.G., and 9 others including P. Dahl, "The detection of seismicity on icy ocean worlds by single-station and small-aperture seismometer arrays," Earth Space Sci., 9, doi:10.1029/2021EA002065, 2022.

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1 Mar 2022

To better prepare for future planetary missions, we deployed seismometers on glaciers and ice sheets, environments on Earth that mimic those of icy ocean worlds. We compare the ability of a single seismometer versus several seismometers in detecting different types of earth and ice quakes and to compare widely different sites with respect to local environmental noise such as ice cracking, melt water from the glacier, and rock falls off nearby mountains. We find that multiple instruments separated by only 1 m can better detect large tectonic events than only one instrument. Further, if the site has low level of environment noise, we detect more large tectonic events. Small local events, however, can help characterize the local environment. We also detected events from equipment left at our field site. Future missions would benefit from sending multiple seismometers instead of just one. If a mission wants to study the whole planet or moon, then the landing site should be situated away from any active surface features and a single seismometer should be sufficient. If the goal is to study a specific active feature or region, then the landing site needs to be close to that feature.

More Publications

Inventions

Acoustic Intensity Sensor Using MEMS Triaxial Accelerometer and MEMS Microphone

Record of Invention Number: 48987

David Dall'Osto, Peter Dahl

Disclosure

30 Jun 2020

Automatic Implementation of NOAA Marine Mammal Guidelines

Record of Invention Number: 48478

Peter Dahl, David Dall'Osto

Disclosure

13 Nov 2018

Airborne Acoustic Particle Motion Sound Meter

Record of Invention Number: 48135

David Dall'Osto, Peter Dahl

Disclosure

1 Aug 2017

More Inventions

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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