Our national parks are getting noisier.

It's partly because more and more people are using them. But it's also due to the outside world closing in.

Flight paths, distant roads, helicopter tours, and other aural detritus of our civilization intrude on the very spots that have been set apart from the impact of the modern world.

Acoustic ecologist Gordon Hempton, for one, is alarmed. Take Yosemite National Park. According to Gordon, "Yosemite Valley was described by John Muir, the father of our national parks and in part the founder of Yosemite, as a musical instrument. However, these days, the alarm clock is not the morning jay—it's the 5:00 in the morning dumpster pickup."

To quiet things down, Gordon campaigned to establish One Square Inch of Silence, which lead to the designation of a small corner of Olympic National Park as a pristine soundscape on Earth Day in June 2005. The campaign's goal was disarmingly straightforward: Restore the sound of nature in our national parks undistracted by the noises of our time.

Says Gordon, "We would no more want to have noise pollution in our national parks than we would want to have smog in Yosemite. National parks are a place to learn, to discover, to discover ourselves as much as nature. I really believe in that old adage that nature discovery is self-discovery."

In these terms, silence is a poetic rather than scientific concept. "I say that silence is something that holds you still so that you can fathom what it is to be alive."

Gordon makes a living collecting sounds and providing audio consultation for everything from nature documentaries to computer games. His hour-long documentary Vanishing Dawn Chorus won an Emmy in 1992. [Check out Gordon's web site.]

GORP feels lucky to have Gordon returning as a guest for Earth Day 2006, where he'll be sharing his favorite sounds, images, and thoughts from the irreplaceable landscape that is Olympic National Park.