PHYS.ORG: Human-caused ocean noise and its dangers to marine life are the focus of meetings at the United Nations this week, a victory for advocacy groups that have long warned of this problem.
What are the causes of ocean noise?
The main human activity that causes noise is maritime shipping.
Among the loudest sounds are explosions aimed at demolishing offshore oil platforms, though these events are rare.
Advocacy groups focus on seismic airguns, which are used by oil and gas interests to find reserves on the ocean floor.
A boat tows 12-48 airguns at a time, each of which shoot loud blasts of compressed air. These sound waves pass through the water and hit the seabed, reflecting back information about buried oil and gas deposits that can be used to create three-dimensional maps.
The blasts are repeated every 15 seconds, over vast areas of the ocean at high volume, sometimes for weeks on end.
