Scientists have put 1.5 million hours of acoustical monitoring to an interesting use: They paired them with data on overhead air traffic and average summer precipitation and turned a computer program loose on the info. The result: a detailed map of America's loudest and quietest places. Science News reports that because the map is relaying the average, the noise level is louder than what's shown about half the time. And while it may come as no surprise that cities tend to experience average noise levels of 50 to 60 decibels, some of the most remote places still get incredibly quiet—in some cases registering lower than 20 decibels, which, as Science puts it, is "a silence likely as deep as before European colonization." But our national parks certainly haven't gone unscathed.
The map was shared at the annual meeting of the American Association for the Advancement of Science, and the abstract on the report notes that "noise elevates median background sound levels by more than 3 decibels in 62% of the coterminous US national parks." The National Park Service plans to use the map to pinpoint precisely where human-made noise might be taking a toll on wildlife. For instance, due to bats' and owls' significantly more sensitive ears, increased noise levels could make it far more challenging for them to make out the subtle sounds of the insects and rodents on which they prey, researchers say. The abstract cites a less-than-soothing finding for the rest of us: "These data show that most people live in environments where night skies and soundscapes are profoundly degraded." (Scientists determined this was the most irritating sound.)