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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 sardines (Sardinops sagax)

Dahl, P.H., A.K. Jenkins, B. Casper, S.E. Kotecki, V. Bowman, C. Boerger, D.R. Dall'Osto, M.A. Babina, and A.N. Popper, "Physical effects of sound exposure from underwater explosions on Pacific sardines (Sardinops sagax)," J. Acoust. Soc. Am., 147, 2383-2395, doi:10.1121/10.0001064, 2020.

More Info

20 Apr 2020

Explosions from activities such as construction, demolition, and military activities are increasingly encountered in the underwater soundscape. However, there are few scientifically rigorous data on the effects of underwater explosions on aquatic animals, including fishes. Thus, there is a need for data on potential effects on fishes collected simultaneously with data on the received signal characteristics that result in those effects. To better understand potential physical effects on fishes, Pacific sardines (Sardinops sagax) were placed in cages at mid-depth at distances of 18 to 246 m from a single mid-depth detonation of C4 explosive (4.66 kg net explosive weight). The experimental site was located in the coastal ocean with a consistent depth of approximately 19.5 m. Following exposure, potential correlations between blast acoustics and observed physical effects were examined. Acoustic metrics were calculated as a function of range, including peak pressure, sound exposure level, and integrated pressure over time. Primary effects related to exposure were damage to the swim bladder and kidney. Interestingly, the relative frequency of these two injuries displayed a non-monotonic dependence with range from the explosion in relatively shallow water. A plausible explanation connecting swim bladder expansion with negative pressure as influenced by bottom reflection is proposed.

Estimation of seabed properties and range from vector acoustic observations of underwater ship noise

Dahl, P.H., and D.R. Dall'Osto, "Estimation of seabed properties and range from vector acoustic observations of underwater ship noise," J. Acoust. Soc. Am., 147, EL345, doi:10.1121/10.0001089, 2020.

More Info

17 Apr 2020

The Intensity Vector Autonomous Recorder (IVAR) simultaneously measures acoustic particle velocity and pressure. IVAR was deployed during the 2017 Seabed Characterization Experiment (SBCEX) with the primary objective to study sound propagation in fine-grained, muddy sediments. In this study a Bayesian inversion framework is applied to ship underwater noise recorded by IVAR. The data are relative phase of pressure and vertical particle velocity, a quantity that is independent of the ship noise source spectrum. Inversion estimates for the sediment layer and underlying basement properties are in agreement with other reports from SBCEX.

Short-range signatures of explosive sounds in shallow water used for seabed characterization

Wilson, P.S., D.P. Knowles, P.H. Dahl, A.R. McNeese, and M.C. Zeh, "Short-range signatures of explosive sounds in shallow water used for seabed characterization," IEEE J. Ocean. Eng., 45, 14-25, doi:10.1109/JOE.2019.2934372, 2020.

More Info

1 Jan 2020

Small explosions were used as sound sources in the Seabed Characterization Experiment conducted in spring 2017 in the New England Mud Patch, a shallow-water region with a depth of approximately 75 m. The sources were U.S. Navy Signal Underwater Sound (SUS) Mk 64 charges, which contained 31.18 g of the explosive 2,4,6-Trinitrophenylmethylnitramine, commonly referred to as Tetryl. Source recordings were obtained by two hydrophones deployed from the same ship that deployed the SUS. The recordings were analyzed for bubble period, energy spectral density, and the variability of these parameters, and compared to previous results from the literature, including the prediction of a historic spectral model, and a new semiempirical time-domain model assembled using measured data from the literature. The new model describes the source level measurements in the 25–275-Hz band and in the 400-Hz octave band to within 0.5 dB, and agrees with similar measurements from the literature to within 0.6 dB. The standard deviation of the band-limited source levels was found to be about 1 dB, some of which is ascribed to uncertainty and variation in the source-to-receiver distance. The observed source level variation is similar to previously reported values.

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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