It’s getting more difficult to get away from it all.

Noise pollution in many of the nation’s national parks and wildlife areas is at significant levels, diminishing visitors’ wilderness experience and challenging wildlife, a new study reports. Sounds of human activity – automobile traffic, jet planes, construction, resource extraction – can overwhelm the subtle soundtrack of the natural world: insects, birds, frogs, wolves, wind and rain.

The first-of-its kind study by researchers at Colorado State University and the U.S. National Park Service, published May 5 in Science, documents the extent to which human noise is encroaching even into remote, protected areas of the U.S.

Scientists found that unwanted noise was twice as high as background sound levels in nearly two-thirds of U.S. protected lands across the country. Intrusive noise was ten times greater in 21 percent of the sites, meaning that sounds once detectable from 100 feet away could now only be heard from 10 feet away.

This anthropogenic, or human-caused, noise was found to substantially affect critical habitat areas for endangered species.

Noise levels found in the study can be harmful to visitor experiences, human health and the health of wildlife, said Rachel Buxton, postdoctoral researcher in the Department of Fish, Wildlife and Conservation Biology at CSU.

“These issues have pretty big consequences for entire ecosystems,” Buxton said. “Noise pollution has real impact on animals,” overwhelming cues that help them find food, seek mates, establish territories and avoid predators.

The scientists, including a special unit of the National Park Service, measured local noise levels, temperature and atmospheric conditions at 492 protected natural areas over the past decade. They recorded nearly 1.5 million hours of sound, using computers and artificial learning systems to determine what sounds were natural and what sounds where made by people. 

Buxton and her colleagues mapped the extent of the noise in American wilderness. The information also helped predict current sound levels for the entire U.S.

Buxton said the researchers were encouraged that sound levels in many large wilderness areas are close to natural levels. There are many opportunities for people to experience the natural soundscape across the U.S., but these relatively unaffected systems need to be recognized and protected, Buxton added.

Noise mitigation efforts in some protected natural areas include shuttle services to reduce traffic, designated quiet zones where visitors are encouraged to quietly enjoy protected surroundings, and the creation of noise corridors through methods such as routing flight patterns over roads.

Researchers hope that more people will consider sound as a component of the natural environment and will come to consider noise pollution as pollution.

“Next time you go for a walk in the woods, pay attention to the sounds you hear – the flow of a river, wind through the trees, singing birds, bugling elk. These acoustic resources are just as magnificent as visual ones, and deserve our protection,” said Buxton.

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