Stick your head underwater near a reef and you may hear the sound of bacon frying. The tempting sound comes from the near-comically oversized claws of snapping shrimp — they slam shut fast enough to create bubbles of air that disappear with a loud pop. The crackling of countless shrimp clacking together is mixed with fish grunts, whale and dolphin calls and other sounds underwater to create what’s called the oceanic soundscape. It’s the kind of biological white noise you might fall asleep to at night.
But one group of researchers think they have another use for the ocean’s background noise. Scientists funded by the military’s research arm, DARPA, the Defense Advanced Research Projects Agency, think tuning in to the chorus of the sea might allow them to detect the near-silent passage of underwater drones. In recent years, the U.S., China and Russia have all been developing fleets of drone submarines — including some that can carry nuclear weapons. At the same time, Russian submarines have been increasingly active in the Atlantic Ocean. Last year, Russia claimed to have sailed submarines just off the U.S. East Coast without being detected.
