Mic Drop

Scientists listen in on the sounds of the deep ocean.

March 07, 2016

The hydrophone gets hauled up from the Challenger Deep mission.
Photo: NOAA

It’s hard to find true peace and quiet anywhere these days, but youd think you’d have some luck escaping humanitys din at the bottom of the sea. Not so, says a team of researchers from the National Oceanic and Atmospheric Association, Oregon State University, and the U.S. Coast Guard. The scientists dropped a hydrophone to a depth of more than 36,000 feet in the Mariana Trench and were surprised to hear all kinds of sounds. You would think that the deepest part of the ocean would be one of the quietest places on earth, says chief scientist Robert Dziak of NOAA. Yet there really is almost constant noise from both natural and man-made sources.

With sonar, military testing, and oil and gas exploration, anthropogenic noise at sea has steadily increased in recent years. To help determine how the rising ruckus is affecting marine mammals, scientists wanted to establish a baseline for ambient noise in the deepest parts of the Pacific Ocean. For three weeks, they recorded sound waves in the Challenger Deep trough, nearly seven miles beneath the surface. Among the sounds the hydrophone overheard were earthquakes, a category 4 typhoon that happened to pass by overhead, moaning baleen whales, and plenty of ship traffic. Listen to some samples below.

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