Summary: First sound records of acoustically clear super deep Challenger Deep reveal a busy baseline of natural and man-made sounds, according to NOAA March 1.
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| closeup of titanium-encased, ceramic hydrophone being lowered into Challenger Deep trough in Mariana Trench, 2015; white basket atop pressure case protects hydrophone element: Public Domain, via National Oceanic and Atmospheric Administration (NOAA) |
First sound records of acoustically clear super deep Challenger Deep capture an expressive ambient noise baseline of natural and manmade sounds, sharply audible at a depth of 6.83 miles (10.99 kilometers), according to findings released March 1, 2016, by the National Oceanic and Atmospheric Administration.
“You would think that the deepest part of the ocean would be one of the quietest places on Earth,” Robert P. Dziak, director of the Acoustics Program for the Ocean Environment Research Division (OERD) of NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Newport, Oregon, explains in the news release. “Yet there really is almost constant noise from both natural and man-made sources.”
The busy first sound records of acoustically clear super deep Challenger Deep contrast sharply with the eerie quiet experienced by Canadian film director James Cameron in his deep-sea descent into the Mariana Trench’s deepest known point. Cameron’s successful descent two leagues under the sea in Deepsea Challenger on Monday, March 26, 2012, fulfills a lifelong ambition. Cameron’s dive also gains distinction as one of only two successful descents to the Challenger Deep by a manned submersible. Jacques Piccard and retired Navy lieutenant Don Walsh achieve the first successful descent to Challenger Deep’s seemingly quiet, deep realm on Saturday, Jan. 23, 1960, in Trieste, a bathyscaphe co-designed by Jacques and his physicist father, Auguste.
A titanium-encased hydrophone, however, moored about 30 feet (9.1 meters) above Challenger Deep’s floor in July 2015, reveals a wonderfully sound-filled watery world. Marine life and natural events contribute to the clear, steady, deep-sea cacophony that fills the flash drive within about 23 days.
“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,” explains Dziak.
Manmade noises join natural sounds in the first sound records of acoustically clear super deep Challenger Deep.
“There was also a lot of noise from ship traffic, identifiable by the clear sound pattern the ship propellers make when they pass by,” says Dziak. “Guam is very close to Challenger Deep and is a regional hub for container shipping with China and the Philippines.”
call of dolphin or toothed whale
sounds of baleen whale that might be a Bryde’s whale
5.0 magnitude earthquake on July 16, 2015, near Guam, at depth of over six miles (10 kilometers) in ocean crust
steady rhythm of distant ship’s propeller
Haru Matsumoto, assistant professor and senior researcher at Oregon State University in Newport, and Chris Meinig, director of engineering at NOAA’s Pacific Marine Environmental Laboratory in Seattle, design the ceramic hydrophone to withstand extreme pressure and temperature changes. The hydrophone is lowered from U.S. Coast Guard cutter Sequoia painstakingly slowly down through the Pacific Ocean in July 2015.
Sea level atmospheric pressure averages 14.7 pounds per square inch (PSI). The target depth in Challenger Deep exerts a crushing force of more than 16,000 pounds per square inch.
“We had to drop the hydrophone mooring down through the water column at no more than five meters per second to be sure the hydrophone, which is made of ceramic, would survive the rapid pressure change,” recalls Matsumoto.
Busily scheduled ship traffic and persistent typhoons delay retrieval of the hydrophone by Guam-based Sequoia until Nov. 3, 2015. An acoustic signal sent from Sequoia releases the hydrophone from its Challenger Deep mooring. Colorful orange floats attached to the line allow for the hydrophone's safe ascent to the surface.
The project yielding the first sound records of acoustically clear super deep Challenger Deep represents a collaboration between Oregon State University’s Hatfield Marine Science Center (HMSC) in Newport and two funding partners, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Coast Guard.
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| image by the University of New Hampshire's Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM-JHC): The Oregonian @Oregonian via Twitter March 3, 2016 |
Acknowledgment
My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.
Image credits:
Image credits:
hydrophone closeup: Public Domain, via NOAA @ http://www.noaa.gov/seven-miles-deep-ocean-still-noisy-place
image by the University of New Hampshire's Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM-JHC): The Oregonian via Twitter March 2, 2016, @ https://twitter.com/Oregonian/status/705256501556989952
For further information:
For further information:
NOAA. "Seven miles deep, the ocean is still a noisy place." March 2, 2016.
Available @ http://www.noaa.gov/seven-miles-deep-ocean-still-noisy-place
Available @ http://www.noaa.gov/seven-miles-deep-ocean-still-noisy-place
Oregon State News and Research Communications. "Mariana Trench: Seven miles deep, the ocean is still a noisy place." March 2, 2016.
Available @ http://oregonstate.edu/ua/ncs/archives/2016/mar/mariana-trench-seven-miles-deep-ocean-still-noisy-place
Available @ http://oregonstate.edu/ua/ncs/archives/2016/mar/mariana-trench-seven-miles-deep-ocean-still-noisy-place
The Oregonian. "OSU and team of researchers deploy hydrophone to record rumbles from Mariana Trench." YouTube. Wednesday, March 2, 2016.
Available @ https://www.youtube.com/watch?v=PXyQw61tdTI
Available @ https://www.youtube.com/watch?v=PXyQw61tdTI
The Oregonian @Oregonian. "Oregon researchers find mixture of sounds in the Mariana Trench. Listen to the recordings." Twitter. March 2, 2016.
Available @ https://twitter.com/Oregonian/status/705256501556989952
Available @ https://twitter.com/Oregonian/status/705256501556989952
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