Mysterious Sounds from the Deep Ocean

Tuesday, November 7, 2017 by Natasha

A few weeks ago, a student visiting GMRI for a LabVenture! experience with Brunswick Jr. High asked if I had ever heard of “Upsweep” before, which I had not!

“Upsweep” is a deep ocean sound recorded by NOAA’s Pacific Marine Environmental Laboratory (PMEL) Acoustics Program. The noise was first recorded in August 1991, and can be heard throughout the Pacific as a series of upsweeping sounds. The sounds occur seasonally, reaching its highest volume in the fall and spring, and is believed to originate out of the South Pacific Ocean. However, the biggest question remains: What is causing the “Upsweep” sound? While hypotheses have been formed, scientists have yet to discover the source of this mysterious sound.


The main reason NOAA monitors underwater ocean noise is because it “is critically important to understand[ing] both natural and [human driven] changes in the marine ambient sound environment” ( This means, scientists, through ocean noise research, can better understand the how marine life communicate through sound, and how marine life is affected by sound.


The South Pacific is not the only area of the ocean being monitored. In fact, the Gulf of Maine is home to several ongoing acoustic monitoring projects today. This includes data collection on baleen whale distribution, data collection to help reduce the impact on right whales, and data collection used to map Atlantic cod spawning grounds. To learn more about these monitoring programs, click this link:


Deep ocean sound is yet another tool scientists use every day to better understand the wonders of the underwater world, and sometimes, like with the “upsweep,” ocean sounds remain a mystery!


Click here to listen to the undefined “upsweep” sound!

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