The Mariana Trench is well known and often cited by know-it-all third graders you babysat for that one time, as the deepest part of our ocean system. It’s pretty much the closest to the middle of the Earth you can drop a penny and hope it will sink to, if such a thing appeals to you. OSU researchers decided to go a little further than that and sent a titanium-shielded hydrophone down there to record the noises. What they heard blew their minds.
Robert Dziak is a NOAA researcher with a courtesy appointment to OSU’s College of Earth, Ocean, and Atmospheric Sciences (CEOAS). He was the chief scientist on the project, and he expected to not hear much when he dropped the mic—36,000 feet deep.
“There really is almost constant noise from both natural and man-made sources. The ambient sound field at Challenger Deep is dominated by the sound of earthquakes, both near and far as well as the distinct moans of baleen whales and the overwhelming clamor of a category 4 typhoon that just happened to pass overhead,” said Dziak in a press release about the findings. “There was also a lot of noise from ship traffic, identifiable by the clear sound pattern the ship propellers make when they pass by.”
The Challenger Deep is a part of the famed trench that is particularly deep, near Micronesia and Guam. Those were the sources of the ship sounds they heard on the recordings.
Getting recordings at such depths is incredibly difficult. The pressure can get up to 16,000 PSI, versus about 14.7 in your living room. A lot of equipment, unsurprisingly, can’t withstand that kind of pressure and would crush like an empty soda can… or your dreams.
Haru Matsumoto is one of the OSU engineers tasked with getting a microphone to work down there.
“We had never put a hydrophone deeper than a mile or so below the surface, so putting an instrument down some seven miles into the ocean was daunting,” Matsumoto said in the press release. “We had to drop the hydrophone mooring down through the water column at no more than about five meters per second. Structures don’t like rapid change and we were afraid we would crack the ceramic housing outside the hydrophone.”
Will this project have long-ranging implications in acoustics science and oceanography? Undoubtedly. Will it also possibly lead to an underwater Jack White album? Time will only tell. Thankfully, OSU has now made that future a possibility.
By Sidney Reilly