Colorado State University Researchers Say ‘Hush’ in National Parks

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While visiting a national park most people would not think of natural sounds and solitude as endangered species they would expect to encounter. Two new Colorado State University studies published recently in Park Science Journal indicate that visitors to the Bear Lake Corridor of Rocky Mountain National Park need to hike just more than a half-mile to get some peace and quiet.

Research has shown visitors to national parks can potentially impact natural aspects of parks by trampling fragile vegetation, compacting and eroding soils, polluting water and disturbing wildlife. Colorado State researchers are now finding that acoustic impacts are also prevalent in national parks.

Human-caused sounds from aircraft, roads, maintenance activities, and other visitors and the permeation of noise pollution, make natural sounds and quiet an increasingly scarce resource.

CSU scientists conducted research at Rocky Mountain National Park by modeling and mapping visitors’ exposure to transportation-related noise while visiting attractions and hiking on trails in the popular Bear Lake trailhead and road corridor.

The study found that transportation sounds from Bear Lake Road permeate the park’s acoustical environment throughout the adjacent trail system. The noise is concentrated along the road and falls off sharply with distance and changes in topography. However, the extent of noise in the area requires little effort on the part of visitors to reach areas of quiet away from Bear Lake Road. Visitors that follow the most direct routes to quiet areas would have to walk more than half a mile.

Researchers calculated visitors’ average hiking speed at 1.2 mph. This hiking speed is lower than typical average hiking speeds for other areas because of many groups’ propensity to linger or move more slowly around attraction areas such as Bear Lake and because of the relatively steep terrain. This hiking rate, coupled with the hiking distance results, suggests that visitors would have to hike between 6-51 minutes, depending on the trailhead selected, to reach quiet areas of the park.

“People want quiet,” said Peter Newman, associate dean of academics in CSU’s Warner College of Natural Resources and co-author of the study. “As people hike trail networks, more often than not they value the solitude, peace and quiet of wilderness. Findings from this study can help provide park management with understanding of the type and extent of noise visitors are exposed to during their recreational experience. It also provides information about the types of acoustic opportunities visitors may have on specific trails.”

Newman co-authored another study published in this month’s Park Science Journal that studied different techniques and methods to establish “quiet zones” in Muir Woods National Monument in California.

“In this study we specifically looked at how we can quiet people who come and visit national parks because we know that too much noise pollution generated by people can degrade visitor experience,” said Newman. “Essentially we used the method used by libraries and created signs that specified areas of quiet. The signs warned people when quiet zones were coming up and we found that it worked. By zoning for quiet areas we lowered the sound level three decibels. This is essentially a doubling in the area in which visitors could hear things like wildlife or a babbling brook.”

Findings from both of these studies provide insights on the acoustical environment, route decisions of visitors, overall visitor use and demonstrate the effectiveness of implementing quiet zones so that now park management can proactively and deliberately assess the effects on the soundscape.

Newman will present some of these findings next week at Rocky Mountain National Park’s Research Conference in Estes Park.

These studies reflected a collaboration among scientists at the Resources Systems Group, Inc., Utah State University and Colorado State University graduate students David Pettebone, Adam Gibson, Derrick Taff and Lelaina Marin.

The current issue of Park Science Journal contains articles written by more than 12 CSU faculty, doctoral students, graduate students and alums. The journal is available at