Even in wintertime Denali Park, the near-extinction of silence

Since 2006, the National Park Service has been recording monthlong soundscapes in Denali National Park, part of an effort to learn how the noise of human activity changes -- or endangers -- wildlife and wilderness habitat. Park service technician Davyd Betchkal tells The New York Times that in all that time, there have been only 36 days in which recording equipment didn't detect an airplane, snowmachine or the distant roar of a passing train. The tourist season is loudest, of course, he says, but sound can travel far in the still air of winter.

That sort of human din, studies are beginning to suggest, is imperiling habitat -- in Denali as well as wilderness areas around the world -- as surely as a bulldozer or oil spill. But scientists have so little information about what landscapes should sound like without human interference that trying to correct the problem would be like a surgeon's wielding a scalpel without knowing the parts of the body, let alone his patient's symptoms. To restore ecosystems to acoustic health, researchers must determine, to the last raindrop, what compositions nature would play without us. ...

Species can fight for airtime in a limited bandwidth by changing their volume or frequency, or by rescheduling the timing of their calls. But there’s no way animals can alter their ability to listen — for their very survival — if human noise conceals, for example, the twig-snap of a prowler or the skittering of prey. In the United States, where more than 80 percent of land is within two-thirds of a mile of a road, the listening area available to most creatures is rapidly shrinking.

In the article for the Times' Sunday magazine, correspondent Kim Tingley accompanies Betchkal on a hike up the Hines Creek watershed a few miles west of the Denali Park headquarters to install an acoustic data station -- a difficult task in winter. Later, back in Betchkal's office, they listen to other captured sounds.

"I love this clip," he said, pressing play on his computer. We heard a snuffling at the microphone and, nearby, the bellowing of babies that were actually bear cubs. "Part of my job is to go around and document these rare sounds," he said, "to better understand the resource that needs to be protected - are there really important sounds out there that are disappearing?" He clicked again, and the tinny gurgle of an ice cave filled the speakers. "There's thousands of little bubbles," he said in narration. "I imagine like a big cave, and each room of the cave probably has different ways of reflecting sound. We can share sounds with people who might not be able to walk up to that ice cave and go hang around inside of it. Maybe even better, it excites them enough that they're like, All right, let's go on a hike! We're going to check out an ice cave! Or whatever."

Read much more at The Times, where you can also play audio clips of sounds mentioned above and more.