Mathematician Michael Porter and geologist Laurel Henderson, who mapped the noise, say they hope a better understanding of the ocean’s “soundscape” will be used to help find ways to reduce its impact on marine life.
Ocean noise pollution caused by commercial and military ships is considered a threat to whales, dolphins, fish and squid, which use sound to navigate, feed, and avoid predators.
Because sound waves can travel much farther underwater than through the air, the loud chop of a single propeller can confuse and even physically harm animals hundreds of miles away.
Part of Porter and Henderson’s soundscape project includes mapping areas where underwater sound can travel very easily compared to those regions where noise tends to be more muffled.
Flat, sandy ocean floors echo sound much more effectively than a craggy undersea mountain range.
“The most important thing about these maps is that seeing the sound can get people thinking about its effects,” explains Porter, who is the CEO of Heat, Light & Sound Research Inc., an underwater acoustics technology company in San Diego.
Such information could inform decisions about where to best place ship traffic routes. The data could also help researchers understand how environmental changes like ocean acidification will affect the undersea soundscape.
While Porter and Henderson call their noise model just a small step towards understanding the effect that human-generated noise has on the marine ecosystem, other researchers are delving into this issue as well.
In a study published last April, mechanical engineers and physicists at the University of Washington found that pebbles and sediment being pulled back and forth along the seabed can generate a massive amount of noise.
This is a significant finding for those hoping to harness tidal power, a renewable power source that can be generated by turbines built on the ocean floor to spin back and forth with the tide’s ebb and flow.
Depending on how noisy the shifting pebbles and sediment are, building such turbines could harm local sea creatures, which may not be able to hear the whirling blades over the natural cacophony of the sea.
Photo: U.K. Navy