As the number of people visiting Alaska and national parks breaks records, acoustic measurements of quietude or wilderness-ness are becoming more important to employees of the National Park Service who view sound as part of the ecosystem. The twenty-some members of the Natural Sounds and Night Skies Division are creating long-term recordings across the parks to determine if and how humans and their sounds may be altering park experiences of both visitors and wildlife.

“Old-timers say the one thing that’s gotten worse, or changed, is how much noisier it’s gotten,” said Davyd Betchkal, an ecologist who works in Alaska for the division. But there are still places he can go for 24 hours without hearing the sound of a combustion engine. “If I ever have kids, I want them to be able to come to Alaska and have experiences similar to the ones I’ve had,” he said.

Karupa Lake is perhaps the premier place for solitude, pure wilderness and intact nature in the whole national park system. This past summer Mr. Betchkal sent Noah Hoffman, his assistant and now a graduate student at the University of Colorado, Boulder, there to get a baseline reading of the types of sounds you’d expect to hear — and the unnatural sounds you wouldn’t. They got almost three weeks of sound before the bear destroyed the recording station.