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August 24, 2001 — Casual observers often imagine that the depths of the ocean are dark, still, and quiet, but those who work in and with the ocean know that there is a lot going on under the surface. (Click NOAA image for larger view.)

"There are a lot of things making noise down there," said Christopher Fox, director of the Acoustic Monitoring Project from NOAA's Pacific Marine Environmental Laboratory in Seattle. "In addition to the rumblings of the earth, there are sounds made by whales, dolphins, and fish."

Fox will head a project to install underwater hydrophones—electronic "ears"—that will hear these noises and send them back for researchers to study. The first hydrophone will be installed Sept. 1 on a submarine cable at Pioneer Seamount off the California coast and will soon be sending back digital data that will be made available to the public via the Internet as part of a Sound in the Sea project.

"We will be listening for many things, such as underwater earthquakes, volcanoes, and landslides," said Fox. "This will also help us track large marine mammals as they migrate along the West Coast."

The ocean's unique properties allow sound to propagate—or travel—over great distances with very little signal loss. Ice breaking up and "calving" or separating from the main ice sheet or glacier in Antarctica or Greenland can be heard by a hydrophone many miles away. Some ambient noise includes wind, precipitation, surface waves, and lightning strikes.

Fox notes that natural phenomena are not the only source of sound in the sea. Since the Industrial Revolution of the 1850s, humans have been producing increasingly significant amounts of ocean noise from steam ships to today's supertankers and container ships.

"NOAA's Sound in the Sea project is the beginning of a larger effort by the scientific community to expand our ability to study underwater acoustics on a global basis and to explore the sources of sound and their potential impact on marine life," Fox said.

The expedition to Pioneer Seamount—one of the expeditions under NOAA's new Office of Ocean Exploration—is the first-ever installation of a long-term hydrophone array by a civilian program. NOAA's research vessel, Ronald H. Brown, will be used to install the device.

"While this will be a valuable tool to help us identify and analyze many of the sounds in the ocean, there will still be many sounds that remain mysteries," Fox said. "One example is the ‘bloop,' a sound that has been reported for decades by Navy sonar men, but whose origin has still not been determined."

Relevant Web Sites
NOAA's Ocean Exploration Program

Hear Some Underwater Sounds, including the Mysterious "Bloop"

NOAA's Sound in the Sea Project

NOAA's Pacific Marine Environmental Laboratory

Media Contact:
Jana Goldman, NOAA Research, (301) 713-2483 ext. 181