The technique may offer Homeland Security and the Navy a kinder, gentler method of non-lethal diver deterrent, an alternative to deadly underwater explosive charges or loud underwater sirens, which may impact marine life.
The idea is to detect the diver's breathing passively instead of using an active acoustic technology like a sonar ping. Sutin has recently returned from Holland, where he and a team of Stevens and Dutch scientists investigated passive acoustic methods of diver detection.
"Many fishes can produce similar signals to divers on active sonar, but fishes do not breath like humans" says Sutin. "Passive methods based on the breathing of a diver are such simpler and offer a much better detection rate."
The next step will be to develop a method to isolate a narrow band of the breathing sound and radiate it back to the diver. Using a technique called Time Reversal Acoustics, the scientists hope to produce an amplified beam of sound loud enough to overwhelm an intruder but focused enough to spare the surrounding wildlife.
Time Reversal acoustics has been successfully used to amplify acoustic signals to the level enough to destroy kidney stones.
The talk "Time reversal acoustic approach for nonlethal swimmer deterrent (2pBBa6)" by co-author Yegor Sinelnikov will be at 2:35 p.m. on Tuesday, November 16.
Abstract: http://asa.aip.org/web2/asa/abstracts/search.nov10/asa291.html
Dr. Sutin and Dr. Sinelnikov have written a lay-language paper that describes this research in greater detail. It is available upon request and will be posted to ASA's virtual press room shortly before the meeting.
9) Why Some Voices Sound More Attractive
Some people's voices seem to have been made for the radio. Others grate on our
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| Contact: Jason S. Bardi jbardi@aip.org 301-209-3091 American Institute of Physics Source:Eurekalert |