20,000 Decibels Under the Sea

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Jacques Cousteau took us to the bottom of the ocean and back in his acclaimed 1953 book, Le Monde du Silence (The Silent World). His documentary film bearing the same title won an Oscar in 1957. Today, Cousteau might have chosen a different name for his works, perhaps 20,000 Decibels Under the Sea. 

Cousteau’s undersea world is getting to be a noisy place. You may not have heard the sounds of supertankers, cargo ships, military testing, or oil drilling on your Songs of the Humpback Whales CD, but they’re out there in force. Environmentalists say the ever-increasing racket poses a serious threat to marine animals and that steps should be taken to protect them. At least one perpetrator of underwater noise, the U.S. Navy, is hearing the message loud and clear.

The Navy is drawing fire over its use of a new low-frequency active (LFA) sonar system, which their experts say is essential for detecting superquiet enemy submarines developed for the post–Cold War seascape. It works by generating blasts of sound at upwards of 230 decibels (a jet engine is about 120 decibels at the source) from massive transmitters that ships drag through the water; technicians then interpret the echoes. The Navy wants to use this technology in 80 percent of the world’s oceans.

Jacques Cousteau took us to the bottom of the ocean and back in his acclaimed 1953 book, Le Monde du Silence (The Silent World). His documentary film bearing the same title won an Oscar in 1957. Today, Cousteau might have chosen a different name for his works, perhaps 20,000 Decibels Under the Sea. 

Cousteau’s undersea world is getting to be a noisy place. You may not have heard the sounds of supertankers, cargo ships, military testing, or oil drilling on your Songs of the Humpback Whales CD, but they’re out there in force. Environmentalists say the ever-increasing racket poses a serious threat to marine animals and that steps should be taken to protect them. At least one perpetrator of underwater noise, the U.S. Navy, is hearing the message loud and clear.

The Navy is drawing fire over its use of a new low-frequency active (LFA) sonar system, which their experts say is essential for detecting superquiet enemy submarines developed for the post–Cold War seascape. It works by generating blasts of sound at upwards of 230 decibels (a jet engine is about 120 decibels at the source) from massive transmitters that ships drag through the water; technicians then interpret the echoes. The Navy wants to use this technology in 80 percent of the world’s oceans.

The Navy’s conclusion, that these changes have "no lasting biological significance," raised the ire of critics. "These experiments only tested immediate observable changes in behavior to an exposure level of around 150 decibels, a sound well below the 240 decibel level at which the technology will be deployed," writes marine researcher Leigh Calvez in The Ecologist (June 2000).

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