RESEARCHERS GETTING EARFUL OF OCEAN : NAVY TURNS ACOUSTIC GUITAR OVER TO SCIENCE.

Byline: Judy Telfer Monterey County Herald

For listening to whales, measuring underwater earthquakes or detecting nuclear tests in distant parts of the world, the new Ocean Acoustic Observatory at Point Sur is the place to be.

It looked deserted, with a weedy, never-mowed lawn and buildings that are bare except for two racks of electronics gear and a few computers. Mousetraps baited with cheese sit poised along the walls, awaiting their victims.

A metal box at eye level on one wall opens to reveal a fist-thick bundle of plastic-covered copper wires that lead to an array of 30 hydrophones stretching 25 miles out into the sea.

Last week the Navy turned over the three buildings nearest the shore at the old Point Sur Naval Facility to the Naval Postgraduate School for a consortium of researchers to use to ``keep an ear on the ocean.''

``It's really a national treasure,'' said Ching-Sang Chiu, an associate professor and director of the Coastal Ocean Acoustics Center. ``We can use the facility to learn so much about the ocean.''

Chris Miller, manager of the observatory, said it can be thought of as a telescope looking out into space.

``If you put a telescope out into the water,'' he said, ``you could only see about 30 feet in these waters. Sound is the one thing that can transmit for hundreds of miles in the ocean. The hydrophone array pointing out to the Pacific is the same as the Hubble telescope pointing out to the stars.''

Khosrow Lashkari, a senior research engineer for the Monterey Bay Aquarium Research Institute, said the observatory ``is a multi-million-dollar facility, a national asset, built by the Navy and taxpayers' money, which served its defense purposes during the Cold War.''

What it really is, Lashkari said, ``is a sensor, a means to sense the ocean acoustically, and it can be used for scientific research, such as monitoring biological, geological and physical phenomena. Any kind of phenomena that generates sound can be monitored.''

Research projects so far have included monitoring of the French nuclear test on Sept. 5, 1995, at Mururua in the South Pacific, and one by the oceanography department at the Naval Postgraduate School to listen to data transmitted by instruments drifting in the ocean in a study of the California coastal currents.

In one 13-hour period, two researchers identified 135 distinct whale calls.

Most of the data goes directly into computers and signal processors, but hanging on one rack of equipment is a low-tech-looking set of earphones through which the actual sounds can be heard. On a recent day last week that Miller said was unusually quiet, the sound of the ocean itself was audible: a low, rumbling sound that was more felt that heard.

The Navy considered cutting the cable and not allowing researchers access to the hydrophone array to prevent its ever being used to track U.S. submarines.

Instead, they finally agreed to unconditionally declassify and allow access to one hydrophone out of the array of 30.

Miller said that just as it takes two eyes to have depth perception, it takes a minimum of two hydrophones to be able to pinpoint where a sound is coming from. So with only one hydrophone available, researchers will not be able to track a sound. The other 29 hydrophones, he said, will be available for classified projects, but at this point they are not being used.

So far, the consortium is made up of:

- The Center for Monitoring Research of the Science Applications International Corp., which is using the hydrophone to monitor the nuclear test ban treaty.

- Cornell University's Bioacoustics Research Program, which is what Miller called ``the ATOC police,'' the independent monitor of a sound generator placed at the Pioneer Seamount 48 nautical miles off the coast of Half Moon Bay for the Acoustic Thermometry of Ocean Climate project.

- Monterey Bay Aquarium Research Institute, which is monitoring the ocean acoustically in real time to determine if there's anything taking place in the ocean, whether it is a blue whale or an underwater earthquake.

- Naval Postgraduate School's Meteorology Department, which has instruments on land at the site to record winds and sea breezes.

- Naval Postgraduate School's Oceanography Department, which is doing a two-year study of the circulation of the Monterey Bay National Marine Sanctuary in the hope of learning about coastal upwelling, how thermoclines interact and seasonal variability.

- Scripps Institution of Oceanography, which is the lead agency for the ATOC project and also is interested in monitoring major storms and seismic events in the ocean.

- The University of Washington's Applied Physics Laboratory, which put the sound source on the Pioneer Seamount for the ATOC project and is about to put a second sound source in Hawaii. They also are interested in looking at sound levels off the California shore.

The Point Sur Naval Facility, which opened in 1958 as part of the Navy's underwater surveillance network, has been closed since 1986.

No decisions have been made yet as to what to do with the majority of the facility, Miller said. But, he added, it is likely that the facility's lower parking lot will be given to the state Parks Department to use for parking for its Point Sur Lighthouse tours. At present visitors must park on the side of Highway 1 near the lighthouse.

For many years the hydrophone array at Point Sur was known as SOSUS, or Sound Surveillance System, but more recently was known as IUSS, or Integrated Undersea Surveillance System.

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Photo

Photo: The Ocean Acoustic Observatory at Point Sur enablesresearchers to explore the ocean by listening to the sounds that move through it.

Associated Press