Researchers from the National Oceanic and Atmospheric Administration (NOAA), Oregon State University, and the U.S. Coast Guard wanted to establish a standard for ambient noise in the Challenger Deep trough in the Mariana Trench, the deepest part of the Pacific Ocean. However, contrary to the expectation of finding a calm and silent atmosphere, the researchers discovered that the deepest part of the ocean was filled with noises, both natural and human made. To listen to the sounds at a site that lies 36,000 feet, or 7 miles deep, the researchers dropped a titanium-encased ceramic hydrophone ensuring that the overwhelming atmospheric pressure does not destroy it; the atmospheric pressure at the bottom of the Mariana Trench is more than 16,000 per square inch as compared to 14.7 per square inch in an average home. The device recorded the sounds under water for 23 days and it was found that there was constant noise. Robert Dziak, a NOAA research oceanographer and chief project scientist said that, “The ambient sound field is dominated by the sound of earthquakes, both near and far, as well as distinct moans of baleen whales, and the clamor of a category 4 typhoon that just happened to pass overhead." These findings will help in understanding the life underwater and also the extent to which manmade noises interfere with the underwater creatures.
Read more in Science Daily.