Three tripods similar to this one will be put on the floor of the Delaware Bay. The speaker, roughly the size of a small coffee can, is on the top of the tripod.

NEWARK, DE.--A University of Delaware underwater sound experiment set to begin in July in the Delaware Bay has the potential to provide valuable insight into ways scientists can measure the health of the marine ecosystem.

UD marine scientist Mohsen Badiey, an expert in acoustical oceanography, has been working for more than three years on the Delaware Bay High Frequency Acoustic Experiment, which is aimed at understanding the physics of sound in seawater. UD’s Sea Grant College Program and the U.S. Office of Naval Research support it.

The experiment calls for three small speakers the size of coffee cans to be placed in a triangular formation on the floor of the bay roughly one-half nautical mile from the Fourteen Foot Bank Lighthouse. The lighthouse is eight nautical miles from the Delaware coast and seven nautical miles from the New Jersey coast.

The speakers will emit a low-energy, high-frequency sound that is approximately 1,000 times quieter than a fish finder in a 1-square-kilometer area. The water is approximately 39 feet deep in the experiment area.

The total transmission time over the experiment period is 16 hours. The sound pulses, or "chirps," will last from a few seconds every 10 to 15 minutes to 40 seconds once an hour.

There will also be equipment to passively listen to ocean sounds, such as the lighthouse horn and the noise from outboard motors. All the equipment is connected to computers in the lighthouse, where the data will be processed.

The goal of the experiment is to understand how fluctuations in a high-frequency signal can be used to garner information about the physical dynamics of the bay. The use of sound to record changes in temperature, salinity, density and the current of the water could lead to the development of a real-time acoustic monitoring system.

"By measuring the water’s physical properties we could develop remote sensing tools that would track the health of the ecosystem, much the way ultrasound is used on the body," Badiey said.

Badiey said the passive recording of sounds in the bay could help scientists to gain a greater understanding of how marine life communicates, as well as how human-made sounds affect the environment.

The equipment is expected to be in operation by the first week in July. The experiment will be monitored from UD’s 120-foot research vessel Cape Henlopen for the first week. After that, it will be monitored from a remote location on the Delaware coast.

Periodic visits will be made to the site throughout the test period to check on computer backup tapes and instrumentation. A digital camera will record images of the experiment site and report them back to shore throughout the research project.

The experiment is expected to continue for 90 days. Bad weather conditions or equipment failure could extend the research project through Dec. 30.

The equipment will be recovered following the completion of the experiment.

Contact: Maureen Milford, (302) (302) 831-6408, mmilford@udel.edu
June 21, 2000