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How NOT to Drive in Russia HD AUGUST 24

Ocean sound: The Oregon Coast rules when it comes to ambient noise
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NEWPORT, Ore. - For more than a year, scientists at Oregon State University's Hatfield Marine Science Center deployed a hydrophone in 50 meters of water just off the coast of Newport, Ore., so they could listen to the natural and human-induced sounds emanating from the Pacific Ocean environment.
Their recently published analysis has a simple conclusion: It's really noisy out there.
There are ships, including container shipping traffic, commercial fishers and recreationalists. There are environmental sounds, from waves pounding the beach, to sounds generating by heavy winds. And there are biological sounds, especially the vocalizations of blue whales and fin whales. And not only is Oregon's ocean sound budget varied, it is quite robust.
"We recorded noise generated from local vessels during 66 percent of all hours during the course of a year," said Joe Haxel, an OSU doctoral student who is affiliated with both the Cooperative Institute for Marine Resources Studies (CIMRS) and NOAA's Pacific Marine Environmental Laboratory acoustics program at the Hatfield center. "In fact, there is an acoustic spike during the opening of the commercial crabbing season related to the high number of boats working the shallow coastal waters at the same time.
"But, at times, the biggest contributor to the low-frequency sound budget is from the surf breaking on the beach a few kilometers away," he added. "That's where Oregon trumps most other places. There haven't been a lot of studies targeting surf-generated sound and its effect on ambient noise levels in the coastal ocean, but the few that are out there show a lot less noise than we have. Our waves are off the charts."
The year-long study of noise, which was published in the Journal of the Acoustical Society of America, was supported by the Department of Energy, the Oregon Wave Energy Trust, NOAA and OSU.
The study is about more than scientific curiosity, researchers say. The research was carried out in support of OSU's Northwest National Marine Renewable Energy Center and will play an important role in determining whether testing of wave energy devices off the Oregon coast may have environmental impacts.
Scientists must know what naturally occurring sounds exist, and at what levels, so when new sounds are introduced, there is some context for evaluating their intensity and impact.
Documenting marine noises for an entire year isn't easy, the researchers pointed out. First, the equipment must withstand the rugged Pacific Ocean, so the OSU researchers deployed the hydrophone near the seafloor in about 50 meters of water so violent winter storms wouldn't destroy the instrumentation. They focused on low-frequency sounds, where the majority of noise emitted by wave energy converters is expected to occur.
After combing through an entire year of data, they determined that Oregon's low-frequency noise budget is often dominated by the constant sounds of breaking surf. These weren't necessarily the loudest noises, though.
"The strongest signal we got during the course of the year came from a boat that drove right over our mooring," said Haxel, who is pursuing his doctorate through OSU's College of Earth, Ocean, and Atmospheric Sciences. "The second loudest sound came from the vocalizations of a blue whale, which can be incredibly loud. We were told by colleagues at the Marine Mammal Institute that blue whales have been sighted close to shore in recent years and it was probably within several kilometers of the hydrophone."
Haxel said the OSU researchers also recorded numerous vocalizations of fin whales and humpback whales, but a startling omission was that of gray whales, one of the most common West Coast whales.
"We didn't document a single gray whale sound during the entire year, which was really surprising," Haxel said. "Even during times when gray whales were visually sighted from shore within close proximity of the hydrophone, we never recorded any vocalizations. One theory is that they are trying to keep as quiet as possible so they don't give away their location to orcas, which target their calves."

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24 августа 2020 г. 22:31:53
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