What Will the Outdoors Sound Like in the Future?

I'd rented an RV in a several-acre patch of scrubby nothing just outside of Joshua Tree National Park in California. After showing me around the place, my Airbnb host told me about moving here from Los Angeles.

"The first few nights were wild," the host remembered. "Every little noise made us jump, like, 'What was that?'"

I laughed knowingly—I've lived in clamorous Brooklyn for the last four-and-a-half years—but I'd set out on this trip alone for that exact reason: to get some solitude and silence away from the city, immersed in the quiet of the high desert.

But instead of the blissed-out evening I expected, I spent the night acutely aware of my being alone in the off-the-grid camper on a high-alert adrenaline rush, spinning around in the small bed at every noise that pricked out of the silence. What sounded like a roaming, snarling knot of dogs tussled somewhere out in the sandy brush for hours. I knew I'd met a few of those dogs earlier in the day, that they were friendly and lovable, and probably a mile away at my host's own place. To my ears, however, it was as if they were within mere yards of my flimsy camper door.

The next morning, I sat in a lawn chair outside of the RV. The Sun was already up, baking my sleep-deprived face when something rustled above me. Shit, what was that? It croaked and grumbled every few seconds, getting louder. Finally, I spotted the source: a condor, lazily making its way past me and moving on toward the park. It had to have been at least a half-mile away when I first heard its calls, my ears had so adjusted to the quiet.

A few weeks after I'd returned to noisy, big city life, I spoke with Kurt Fristrup, chief of the Science and Technology Branch at the National Park Service Natural Sounds and Night Skies Division. The small office based in Fort Collins, Colorado, sends researchers out to 10 or 20 national parks a year to talk with staff about their soundscape needs, and to deploy sound monitoring systems in the field.

At each of these wild spaces, these bioacoustic scientists spend a few days in "attentive listening exercises," sitting quietly for an hour or two to listen and note every sound, according to Fristrup. They use in-person logs to help process the recordings—studying how often sounds occur, how loud they are, how long each event is—as well as background sound levels, against which all noises are heard.

With a harrowing experience within Joshua Tree's natural soundscape still ringing in my mind, Fristrup and I talked about how our ears work in the wild, and how the Natural Sounds and Night Skies Division is working to make America's remaining wild spaces a little less raucous. Our conversation has been edited for length and clarity.

MOTHERBOARD: What's it like going on an "active listening" exercise for the first time? I'm sure it's very ear-opening, even after a few minutes.
Fristrup: Yes, it's surprising, when you sit down and calm yourself and get as quiet as you can be, how many things you start to notice. If someone's sitting next to you, you begin to hear their heartbeat, too.

Why do humans have such sensitive hearing when it could be, let's say, at least 10,000 times worse and still perform just fine for conversation? We, like all the other animals on the planet, evolved hearing not for communication but rather for environmental awareness: this sort of panoramic, always-on alerting sense that tells us what's going on in the environment around us.

When you sit in these quiet places, it's like standing on a high ledge and perceiving an enormous vista with your eyes. You become aware, and your awareness gradually moves out until you are conscious of this expansive soundscape around you.

That's an experience many people probably haven't had in their lifetimes, just sitting intentionally and quietly in nature for an hour.
It's a rare thing to do. For most people, the opportunities to go out in nature are rare, and when they do, they're being active in some way: hiking, cross-country skiing. It is, I think, rare that people do get the chance to go out into a park—even a local park—and just sit.

The things you can hear from very far away feel like they're right on top of you.
I just came came back from a vacation with my wife in Chaco [Culture National Historical Park] canyon in New Mexico. At one point I'd gotten ahead of her on a trail, and I started hearing her footsteps, and I turned around to say something to her. But she was, like, 100 yards down the trail still. My ears had gotten so tuned to the quiet. Had I been at home and heard those footsteps at that level, she would have been right next to me.

It's really amazing how our ears adjust. I think that this keen sense of hearing evolving for survival is very interesting—that once, we had to be aware of what was coming in plenty of time to get away.
In line with that theme, there are a lot of animals that have lost vision, [like] cave animals [or] animals that live in the soil. There is no known vertebrate species that's [inherently] deaf. In fact, if you included all of the invertebrates, it's astonishing how many different tiny invertebrate animals have evolved different ways of tuning in to sound. It truly is a universal alerting sense.

What happens when you move from an urban environment where there's a fairly steady and predictable diet of sounds, out into a really quiet place, is that all of the sudden there are big gaps between perceptible sounds and the sounds you hear are unfamiliar. So it's that alerting function—maybe one reason why [the condor] seemed scary to you, was that all of the sudden you were getting all of this information that ordinarily in your Brooklyn life is just not part of your experience.

How is human noise pollution impacting wildlife?
There's probably a 40 or 50 year literature showing that the density and diversity of wildlife near roads declines. And you can imagine lots of reasons why that might be true—collisions with cars, perceived risk of all the people and traffic back and forth on the road, pollution, disturbed light and vegetation, the influence of all the headlights. But of course, the other factor it could be is noise.

Just a few years ago a research team at Boise State decided to find out how much of the road effect could be noise, so they hung a bunch of speakers up and down an otherwise undisturbed piece of forest in Idaho that broadcast road noise. They found that migratory birds reacted to what you might call a "phantom road" as if there was actually a road present.

When the noise was off, despite the increased competition, they all gained weight. When the road noise was on, there was decreased competition, but all the birds lost weight.

It's not so much that it's, 'Oh my gosh it's a horrible outcome,' but it gave us an insight that compromised soundscape awareness in terms of things that matter biologically, to be able to find food—and that's something we suspected but didn't know before.

Once we've encroached on that quiet, natural space, can we ever recover the sounds—or silence—that's been lost?
The good news is that unlike other forms of pollution, you can fix the situation as soon as you address the noise source. And there are many ways to reduce noise in the environment, both in terms of making quieter vehicles, which for road vehicles is happening all around us now with the transition to hybrid and electric technologies, and work going into quieter pavements, to reduce the tire-road interaction noise. And aircraft in that last 50 or 60 years have gotten quieter, but there are a lot more of them in the sky.

The moment you make a vehicle or road quieter, those benefits propagate throughout the environment. Of course, it might take all the plants and animals a while to recover.

Where is the quietest place in America?
In one sense the most noise-free place you can go is at the base of a loud waterfall or a beach where there's high surf conditions. In those places, noise sources can't intrude. They may be present but the natural sounds dominate, so in some respect they're the most noise-free places, places like rapids in the Grand Canyon or Niagara Falls.

If you want to ask the question, 'What places have the quietest background sound levels?' those tend to be in some of the dryer and more barren Western parks. In general, if you want to go to the superstars of super-quiet conditions, the lowest levels of background noise we've measured have been in places like the crater of Haleakalā National Park in Hawaii, and Great Sand Dunes National Park and Preserve in Colorado, or wintertime in Yellowstone. In all three cases you have a soft porous ground surface that's soaking up a lot of sound energy, along with a location that's generally distant from most noise sources.

Audio courtesy of NPS & MSU Acoustic Atlas/Jennifer Jerrett

Looking toward the future, what will the outdoors sound like? Will we still have these quiet places in 30, 50 years, or are they just going to keep dwindling?
I think we'll have opportunity to restore a lot of soundscapes across the nation at little or no cost. I'm hopeful that many places will improve. I think one of the key drivers will be if everyday people living in Brooklyn or Manhattan or Topeka, Kansas—anyone living in urban environments—appreciate the natural areas near where they live, and realize there's value in preserving quiet places.

There's a lot of emerging research that shows even brief or episodic experience in quiet places has health and cognitive and psychological benefits for people.

I should qualify that by touching back to your experience: There's no question that someone who's used to an urban environment who's in a quiet place for the first time may find it unsettling. And part of that is because of the unfamiliarity of strange and new and different sounds. All the sudden they're getting information from this alerting system that's been more or less dormant and not particularly useful in chronically noisy urban situations. But there's a lot of literature showing that getting outdoors and being active, and in particular in more active natural sound environments, places where there are birds singing and frogs chirping, has health benefits and improves not just mood but mental function.

It's worth taking the time every once in awhile to go to quiet places and sit quietly, because your body will thank you for it.

Even here in New York, in places like Prospect Park, you can feel like you're outside of the city when really you're in a very central part of it. And that's why people go. Because it feels good.
There are havens of relative quiet almost everywhere, near almost everyone. You don't have to travel cross-country to have a healthy soundscape experience.

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