The world's oceans represent our planet's largest potential wild realm–there are still many areas of the deep ocean that have never been seen, explored, or fully mapped by humans. Yet our boat traffic, military surveillance technology, industrial survey techniques, and offshore energy-related development have created a vast web of sound that has made the human presence known throughout the seas.
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In the past couple of years, increasing public, press, legal, and governmental scrutiny has been directed toward "anthropogenic" (or human-caused) noise in the oceans. Surprisingly, very little is known about the extent of anthropogenic noise in the sea, or the effect of such noise on ocean species. Recently, new generations of sub-finding sonar and increasing explorations for oil and gas reserves (both of which produce sounds pulses of well over 200dB) have led many to question whether there are limits to how loud humans should be in the ocean.
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Complicating the situation is the relative variability in the ways that sound travels and dissipates in underwater environments. While it is true that sound often carries far further in water than in air, variations in temperature, seafloor geography, ocean depth, and frequency of the sound all can create vast differences in how far sounds travel and how loud they are when they are received. Moreover, the "natural" sounds of the ocean (especially storm-tossed waves and many species' calls) are also quite loud at times, raising uncertainty about how human noise is different, and how well-adapted ocean creatures may be to extreme sound.
Beginning in the late 1990's, fears mounted after some unexpected whale beachings, in which the animals seemed to have suffered some sort of physical trauma causing hemorraging of internal organs, and which researchers identified as likely caused by acoustic impacts. Other recent research has shown that fish can suffer long-term hearing damage after exposure to sounds in the range generated by seismic survey air guns and new navy sonars. In the wake of these findings, and of governmental reports and court orders that pointed toward the dangers of intense sound on ocean life, several reports emerged in 2002 and 2003 calling for more intensive research and public education into the extent and effects of human-made noise in the oceans.
This section of the AcousticEcology.org website (still under development) aims to offer an overview of various sorts of sounds that are of concern, as well as a primer on the physics of ocean acoustics. It also offers links to key ocean noise reports that have been released over the past several years. Our hope is that through bringing together a wide range of available knowledge, we may contribute to a richer, more informed dialogue between the public, academia, and governmental agencies.
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