This is Scientific American 60-Second Science. I'm Steve Mirsky."Noise can prevent an animal from hearing other important sounds."Rachel Buxton, a conservation biologist at Colorado State University.Buxton and colleagues wanted to see, or rather hear, whether sounds made by human activity-called anthropogenic sound, think airplanes, highway traffic, heavy machinery-were significant in protected areas around the country."Park Service engineers on our team used over a million hours of acoustic measurements taken from 492 sites around the contiguous United States.And they built a sound model...so to get at an idea of noise pollution, we used two thresholds: where anthropogenic noise raises sound levels three and 10 decibels above natural."Which translates to a doubling and 10-times increase in sound levels.Buxton and her team determined that humans were responsible for doubling the sound in 63 percent of protected areas.And we raise the natural sound levels by 10 times in 21 percent of such landscapes."These levels are known to impact both the human experience in national parks and have a range of repercussions for wildlife...so animals use sounds for many essential life functions, such as predator avoidance, navigation, finding food, mate attraction and maintenance of social groups.So not being able to hear these sounds has serious consequences."The study is in the journal Science, which also provided the audio of Buxton."The challenge here is managing noise sources that are coming from outside the protected area...however, our paper provides some really valuable information and options for managing noise and also enhancing opportunities to enjoy natural quiet."Because it's not just the non-human residents of wilderness areas that need some peace and quiet.For Scientific American 60-Second Science. I'm Steve Mirsky.