Diver's Own Breathing Could Be Used to Thwart Attack

(Nov. 16) -- For years, the military has looked at ways to spot -- and stop -- divers and swimmers who could pose a security threat to ports and ships. Now an acoustics expert says he may have found a way to use the sound of a diver's breathing to ward off a potential attack.

"One of the main concerns is a diver coming to port and bringing explosives and other dangerous devices," Alexander Sutin, a research professor at the Stevens Institute of Technology, told AOL News in an interview. "Now we know how to detect the diver, but then how can you stop him?"

David J. Phillip, AP

An acoustics expert says he may have found a way to use the sound of a diver's breathing to stop a potential attack with "time-reversal acoustics," which uses the return path of a sound wave to focus acoustic energy on the originating source.

One answer, Sutin said, may be to use what's known as "time-reversal acoustics," a new area of acoustic research that uses the return path of a sound wave to focus acoustic energy specifically on the originating source. In the case of divers, their breath would be detected by sonar and then amplified back using the time-reversal acoustic effect, creating a level of sound that causes discomfort and creates a nonlethal deterrent.

"The diver acts as an active self-disclosing acoustic beacon," according to Sutin's new paper, which lays out the concept.

Concerns about terrorist groups using swimmers or divers to attack ships or ports has been on the rise in recent years. In 2004, for example, Hamas fighters dressed in wetsuits attacked a beachfront settlement in Gaza.

The U.S. Navy, in response, has looked at ways to spot and deter swimmers and divers, using everything from trained dolphins that can spot and help capture threatening divers to airguns. Another option is acoustic devices, or "sound weapons," which work by sending out unbearable levels of sound.

Sponsored Links

A number of acoustic devices are already employed by the military and law enforcement, including the Long-Range Acoustic Device, which was used in 2005 by a cruise ship to repel pirates off the coast of Somalia. Underwater, high levels of sound also have a nonlethal deterrent effect, Sutin said, but there are concerns about the potential to harm dolphins and other marine life.

Sutin's approach is unique because it's based specifically on using the diver's breath as the source and focus for the sound. The acoustic noise radiated by a diver is used to focus the acoustic energy back to the diver, without affecting the surrounding environment.

Sutin said his and his colleagues' work on time-reversal acoustics grew out of related work sponsored by the Navy and the National Institutes of Health. So far, however, he has not received any funding to work specifically on the nonlethal weapon idea.