here are few places left in the world where you can pitch a tent under the stars and drift off to the haunting sound of howling wolves. It’s a healing, restorative experience to be so grounded in nature. But the scene changes dramatically when a car alarm goes off in the distance, or an airplane rumbles overhead. In that jarring moment, our connection to wilderness sputters and wanes, and we lose a little piece of the pristine experience.
As the world grows noisier, park soundscapes become polluted, just as water becomes polluted with mercury, or air with carbon emissions. Several years ago, the Park Service recognized that natural sound was a resource in need of protection. So in 2001, the Natural Sounds Program was born.
Its mission: to help parks protect soundscapes by monitoring sounds, both appropriate and intrusive—establishing ambient baselines, and assessing potential impacts. But a natural soundscape doesn’t necessarily mean complete silence all the time. Cannons and gunshots make a perfectly acceptable soundscape at Gettysburg National Military Park. “We deal with whatever sounds are appropriate for individual parks and the reasons they were established,” says Karen Trevino, Natural Sounds’ program manager. “Certainly man-made sounds, where appropriate, are every bit as much of the soundscape.”
After measuring sound in dozens of national parks, researchers defined two types of intrusive noises. One is a loud event that catches your attention, maybe even interrupts your activity—like the shrill ring of a cell phone. The second is a broad, diffuse background noise that veils your hearing like smog veils your sight—say, cars on a distant highway.
“Animals have been in the presence of thunderclaps for thousands of years, and presumably, they know how to deal with that,” says Kurt Fristrup, a senior technician with the program. “But gradual elevation of the background noise level means they can’t hear as far out as they used to. It’s potentially a much more serious problem.”
So what’s to blame? Airplanes, snowmobiles, and other motorized vehicles are obvious culprits. An oil pump beyond the borders of Hovenweep National Monument in Utah reverberates like a distant drum through the park. But ironically, a large number of sources come from within, in the form of various Park Service operations.
“We do a lot of things to maintain national parks for our visitors,” Trevino says. “Those things are done out of necessity and aren’t always very quiet.” It’s a unique challenge for the Park Service, and one employees can’t ignore.
The program is too new to provide hard and fast evidence on how wildlife is responding to noise intrusions in the parks. What researchers do know is that animals use sound to hunt, avoid predators, navigate, and find mates. A bull elk might struggle to attract a female if he’s bugling over the steady hum of cars idling on congested park roads. A mouse that relies on its sense of hearing has insufficient warning if a plane muffles a predator’s footfall.
History is telling, too: Endangered gray whales stopped migrating to a lagoon in Baja, Mexico, where they’d been breeding for thousands of years until a salt mine began operating on the coast. “Even though it was an entirely terrestrial operation, this happened almost certainly due to elevated noise levels,” Fristrup says. The mine eventually closed on its own accord, but it took nearly six years for the whales to return.
How does the noise level affect humans? Every day, we’re exposed to the constant hum of cars, televisions, air conditioners, and buzzing fluorescent lights. So we put on our headphones or crank up our white noise machines, and continue to push for technology that masks unwanted sounds, never mind the cost of our hearing.
“It’s one of the sad things about our cities,” Fristrup says. “We learn to ignore our ears because there are noise intrusions all over the place. It’s possible that our urban environments have become so unpleasant that people use music to mask out the sounds, but in so doing they expose themselves to chronic levels that damage their hearing thresholds.”
The national parks beckon Americans with quiet spaces—which poses a challenge, since inviting more people in tends to make a place noisier. “We need to educate park visitors about the importance of the soundscape as a resource, the impact noise has on them, and the impact they in turn have on the soundscape itself,” Trevino says.
She suggests improving on ways people access parks—continuing to promote shuttle programs, for instance—to encourage the most natural conditions. Or investing in different construction materials that help roads better absorb noise. These are just two items on a long list of recommendations for noise control that Trevino’s staff is developing for park managers and maintenance crews.
They’re also joining forces with groups invested in noise-control technology. In 2000, the Park Service partnered with the Federal Aviation Ad-ministration to reduce the number of aircraft flying over Grand Canyon National Park. More recently, the Natural Sounds team led a brainstorming session to encourage information exchange between private companies, nonprofit organizations, and governmental agencies. An even bigger conference is scheduled for 2007.
“We’re in a great position to help forge the development of better tools and technology for the parks,” Trevino says. “It’s cutting-edge science and cutting-edge policy. Our efforts to create a healthier, more enjoyable acoustic environment merely reflect where society as a whole is going. I see the future as a much quieter place than it is today.”
Listen to park soundscapes, accompanied by gorgeous photography, at www.npca.org/magazine/sound.html
Amy Leinbach Marquis is assistant editor for National Parks magazine.
