Bugling elk, rolling thunder, the delicate trill of a hummingbird’s wings. These natural sounds can be heard in America’s national parks—some of the quietest places on Earth.
Along remote trails in the Grand Canyon, natural sound levels are in the 10-decibel range. Rustling leaves in Canyonlands National Park come in at 20 decibels. Compare that to 50 to 60 decibels in a typical suburb.
But natural sounds are increasingly being drowned out by noise pollution. Research recently published in the journal Science shows that 63 percent of protected areas across the U.S. are subjected to noise from planes, cars and machinery. Where you should be able to hear bird song from 100 feet away, now you can often hear it from only 10 to 50 feet.
The Natural Sounds and Night Skies Division of the National Park Service runs the Quiet Parks Program, in collaboration with the Sound and Light Ecology Team at Colorado State University.
They monitor noise levels at selected parks nationwide, including Grand Canyon and Walnut Canyon in northern Arizona. Solar-powered sound recording equipment is placed in locations with representative landforms, plants, animals, and acoustic properties. This equipment captures noise level variations over about 25 days in different seasons.
The aim is to use the data in efforts to reduce park noise, so we can still hear the rustle of leaves and the silence of the canyons.