Taking a Peek in the Deep by Using Your Ears : Oceanography: Scientists at Scripps Institution are developing the concept of ‘acoustic daylight’ to penetrate the underwater darkness.
Scientists at Scripps Institution of Oceanography have developed a method of looking at underwater objects that, oddly enough, is a lot like listening.
The concept has been named “Acoustic Daylight” and is based on sounds created by churning waves.
The sounds spread throughout the ocean’s depths via air bubbles, producing a natural, ambient field of noise, scientists said. Like daylight, the noise is uniform, until it hits an object.
The method developed recently at Scripps uses computer imaging to sketch the object--fish, reef or sunken ship--that disturbs the ambient noise. A few moments later, the image appears on (what else?) a video screen.
Deep-sea video technology, if fully developed, would aid underwater construction and repair, said Scripps physicist Michael J. Buckingham, one of the developers of the system. For example, work on damaged sewage lines, oil rigging and research platforms could be aided by clear viewing in depths of up to 3 miles below the surface, Buckingham said.
The Navy could also use the imaging system, mounted on submarines, to aid navigation, Buckingham said.
Another application, according to Scripps director Edward Frieman, would be as a surveillance camera, like security devices used at automatic teller machines of banks.
Acoustic daylight “cameras” could be used by armed forces, set up at harbor entrances to detect submarines that may be quiet enough to slip through passive listening systems, or that would be picked up as an ambiguous ping on sonar listening devices, Frieman said. The video image provides the advantage of knowing exactly what lurks below.
Fishing companies and environmentalists could use underwater video to monitor shellfish enclaves, reef ecology and ocean vegetation, Frieman said.
“The military and commercial potential is enormous,” said Frieman. “It’s exciting stuff.”
If you can understand it.
Deep sea video is the 4-year-old brainchild of Stewart Glegg, a Florida Atlantic University researcher, and Buckingham, who hypothesized about acoustic daylight and has been developing a crude model of the imaging system at Scripps for about 18 months.
The instruments used now are an acoustic “lens” that looks like a satellite dish and focuses on areas where the noise backdrop has been distorted by an object, Buckingham said. In about two seconds, a computer program translates deviations from the ambient norm into an image.
Right now the image is a light signal, a single dot on a video screen, Buckingham said. As it develops, the lighting will become more intricate, enough to sketch an image. Eventually, the system could be made to produce an image every half second, enough to approximate motion, Buckingham said.
Buckingham and Glegg met in the mid 1980s at the University of Southampton on the southern coast of England. Buckingham went on to study ocean acoustics at the Royal Aerospace Establishment, a government laboratory in Farmborough, England. Glegg is now based in Boca Raton, Fla.
The acoustic experiments were conducted off of Scripps Pier in La Jolla and were funded by the Office of Naval Research. Buckingham and Glegg received $50,000 to conduct two years of experimentation. They have applied for a grant to continue research.
“The acoustic daylight system is still in the very, very early stages of research,” said Marshall Orr, program manager for the Office of the Naval Research Ocean Acoustics Program. “But the results are quite good for the investment. The initial amount was really a minuscule amount of money.” Grants are to be decided upon in May, Orr said.
