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Anthropogenic noise pollution is sound produced by human activities. Anthropogenic noise in the oceans is causing harm and death to marine life. Every ocean in the world is subjected to noise pollution from human activities and the problem is increasing. Over the past sixty years, noise levels in the oceans have doubled every ten years. Navy sonar, recreational boats, commercial boats, offshore drilling, acoustic deterrent and harassment devices and acoustic thermometry, all contribute to the constant barrage of underwater noise in the oceans.
Cetaceans (whales, dolphins and porpoises) rely on sound for survival. They depend on sound to communicate, navigate, feed and bond with each other. Human activities clutter the ocean waters with sounds that mask the sounds of whales and dolphins making communication, navigation and other activities difficult if not impossible for them. Some noise pollution is so loud that exposed cetaceans have gone deaf as a result. It is possible that other marine life is also harmed by anthropogenic noise, but no significant studies have been done on other marine life as of this time.
The large numbers of sea vessels operating on the oceans create a near constant sound in more and more ocean areas. The near constant noise from sea vessels makes communication and navigation difficult if not impossible for a variety of dolphins and whales. A super tanker emits low frequency sounds of approximately 200 decibels, a sound level comparable to an airline jet taking off.
Seismic surveys associated with oil drilling produce loud noises that can damage the hearing of these marine mammals. During seismic surveys, blasts of compressed air are emitted every ten seconds and can produce sounds as loud as 250 decibels.
Acoustic deterrent and harassment devices are used in some ocean areas to deter seals (pinipeds) and porpoises from coming in to the area and competing for fish with commercial fisheries. These deterrent and harassment devices can create noises as loud as 230 decibels.
Acoustic thermometry is a process that scientists use to evaluate average ocean temperatures. Acoustic thermometry produces sounds in the 195 decibel range.
Military sonar used by navies around the world emits low and mid frequency sounds that can travel hundreds of miles away from the source. Because sound travels so well in ocean waters, sonar noise that has traveled hundreds of miles away can sound as loud as it does at the source.
Mid Frequency Active Sonar (MFA) is commonly used by navies around the world. Low Frequency Active Sonar (LFA) is being tested by the United States and could be used in eighty percent of the oceans in the future. LFA noise travels farther in the ocean affecting a larger area. LFA emits louder noises than MFA. The sounds produced by LFA are amongst the loudest sounds human technology is currently capable of producing. Environmental scientists are concerned about the affects LFA will have on marine life if fully implemented.