Birdbrain

 

4

Birdbrain

Most people never listen.

— ERNEST HEMINGWAY

Over the summer, I tried to find a patch of quiet. I spent some time wearing a portable EEG device on my head in different settings, trying to get a sense of which kind of places put me in the holy grail of brain states, the “calm alert” zone prized by Zen masters, surfers and poets. I was after alpha waves. When electricity in the alpha wavelength dominates parts of the brain, it’s a sign that you are not hassled by small distractions, problem-solving or, my peeve, meal planning. Parenting—any kind of caretaking—is a procession of small, endless decisions. Too often, I assume the executive function for the whole family, and I can almost hear my mind stomping out any rogue alpha waves. It’s the sound of brain fry.

Daily aggravations aside, environmental noise deters alphas because we have to either pay attention to the intrusion or actively resist paying attention to it, and that’s work too. I couldn’t quite hit the alpha zone walking in the city parks near my house, and I couldn’t even attain it on a leafy, rural road in Maine either, probably thanks to nearby construction noise, which ended up pissing me off. When my brain waves were later read by the interpreting software, it fired back this message: “This indicates that in this state you were actively processing information and, perhaps, that you should relax more often!”

Even the software was yelling at me. I wanted to yell back, but this would be a mistake. There are no alpha waves when you’re mad.

And the maddening truth is, the world is getting louder.

Can you hear it? “Noise” is unwanted sound, and levels from human activities have been doubling about every thirty years, faster than population growth. Traffic on roads in the United States tripled between 1970 and 2007. According to the U.S. National Park Service, 83 percent of the land in the lower forty-eight states sits within 3,500 feet of a road, close enough to hear vehicles. For planes, the figures are even more dramatic: The number of passenger flights has increased 25 percent since just 2002, and 30,000 commercial aircraft fly overhead per day. In 2012, the Federal Aviation Administration predicted an astounding 90 percent increase in air traffic over the next twenty years. Human activities in general increase background noise levels by about 30 decibels. The official word for the human-made soundscape is the anthrophone.

Stats like those above dismayed Gordon Hempton, a sound engineer based in Washington State who decided to travel the country in search of the few remaining quiet places. By his count, the entire continental United States has fewer than a dozen sites where you can’t hear human-made noise for at least fifteen minutes at dawn. That’s a pretty ridiculously low bar. But it is still so out of reach. The quietest place in the country, Hempton discovered, is a spot in the Hoh Rainforest at Olympic National Park. If you want to hear the earth without us, it’s marked by a red stone on a moss-covered log at 47-degrees 51.959N, 123-degrees 52.221W, 678 feet above sea level. But get there early; by midday, even there, you can hear overflights a dozen times per hour. Noise may well be the most pervasive pollutant in America.

I never thought much about airplane noise until I moved to D.C. I grew up on the eleventh floor of an apartment building in New York, where the sounds of the city were mostly muted and charismatic: a flash of mariachi, a distant ambulance, a summer storm. Out West, the planes were fewer and farther away. But my neighborhood now is one of the loudest in the city thanks to flights following the Potomac River as they roar in and out of Reagan National Airport. Jets fly overhead at a rate of about one every two minutes starting early in the morning, with average decibel levels between 55 and 60 but sometimes spiking much higher (60 decibels is high enough to drown out normal speech; over 80 can damage hearing).

I knew this moving in. Neighbors assured me I would learn to ignore the planes. “After a year or so, you don’t hear them anymore,” they’d said. But it’s been over two years now and I still hear the planes. They drive me crazy. It’s hard to eat alfresco, impossible to talk on the phone with the backdoor open. Between the planes and the routine security surveillance choppers, I feel like I’m in a militarized zone when I walk near the river. My gaze is drawn up, and I can read the logo on the fuselages. Sometimes, I can even make out the theme animal on the Frontier Airlines tail fins. There’s the mustang! It’s wildlife-viewing, D.C.-style.

Then there are the nettlesome sounds of competitive landscaping: the parading whines and drones of weed-whackers, lawn-mowers, leaf-blowers and, if I’m exceedingly unlucky and under deadline, circular saws. Such are the afflictions of close quarters, and they aren’t necessarily new. The Victorian historian Thomas Carlyle didn’t hear engines while working on his biography of Frederick the Great from his study in London, but he was made apoplectic by chickens, carriages and dogs. So maddened was he that he commissioned at great expense the making of a soundproof room in his attic. It nearly killed him. It was so airtight that when he lit up for a smoke, he passed out, only to be saved by the maid.

As Charles Montgomery writes in his book Happy City, “Living under the flight path of commuter jets is terrible for happiness . . . but we do not always respond logically to environmental stimulus.” Right. The logical thing would be to go the hell back to Colorado. My neighbors aren’t exactly wrong. People can become habituated to sound, at least partly. We’ve all heard stories of people who say they can’t sleep if it’s too quiet, or they can’t work apart from a din. Some writers have apps that replicate the sounds of a coffee shop for when they are working at home. I know a New Yorker who now lives in the country, but he plays himself devotionally made recordings of 14th Street, sirens and all, to fall asleep at night.

I keep hoping this settling into noise will happen to me, that I will become inured or even nurtured somehow by the city sounds, but it isn’t happening. In fact, I’ve learned that full habituation is a bit of a pipe dream. Just because you don’t notice certain noises anymore doesn’t mean your brain is not on some level responding to them. Scientists and regulators used to be interested in noise pollution because of the threat of hearing loss, which is real and happening to many of us at younger and younger ages. But even at dramatically lower volumes, noise poses risks far beyond our ear canals. In fascinating studies, people have been hooked up to electrocardiogram monitors while sleeping through plane, train and traffic noise. Whether or not they woke up, their sympathetic nervous systems reacted dramatically to the sounds, elevating their heart rates, blood pressure and respiration. In one study that lasted three weeks, the subjects showed no biological signs of habituating to the noise, and in another study that lasted for years, the biological effects only got worse.

THIS SUBCONSCIOUS VIGILANCE makes sense from an evolutionary standpoint. Sleeping or hibernating animals must still maintain their capacity to react to danger. It’s not uncommon in the animal world for some species to lose their vision through evolution (like bats and those seriously ugly fish at the bottom of the ocean) or their sense of smell (like dolphins, or, increasingly, humans), but there are no known examples of evolution driving vertebrate species to lose hearing. This is our main “alerting” and “orienting” sense; it tells us not only that something is out there but from which direction it’s coming. Sound also triggers our strongest startle reactions.

Of course, nature didn’t intend roaring jet aircraft to be processed by our nervous systems every sixty seconds. What does a loud anthrophone do to us? The news is not good, not for us and not for the birds, whales and other wildlife whose breeding and foraging habits are upended by it. Numerous whale die-off events have been attributed to navy sonar, the vibrations from which literally cause heads to explode. In the remote backcountry of Yosemite National Park, aircraft are audible 70 percent of the time, raising ambient noise levels by about 5 decibels. That’s enough to reduce the distance at which prey species can hear a predator approaching by 45 percent. Lab experiments show that when female gray tree frogs hear traffic noise, it takes them longer to find males who are calling to mate, if they can find them at all. No backseat romance for them.

Sound is designed to be processed swiftly by the brain. Sound waves travel through the air and collide with our eardrums, which wiggle back and forth in response to volume and amplitude. Nerve cells pick up these perturbations and send signals to our auditory cortex, the brain stem and the cerebellum, which together process fear, arousal and motion. As to the perennial question of whether a tree falling in the forest makes a sound if no one is there to hear it (first posed by Irish philosopher George Berkeley), the answer is technically no. There is no sound apart from a sentient brain’s interpretation of molecules vibrating through air or water. The brain turns those molecules hitting the eardrums and pinnae into a mental idea of sound. Birds will hear the toppling tree, and fish will hear it too. But there is no thing called sound unless the vibrating molecules are processed into pitch.

Hearing evolved well before vocalization, and eventually became useful for communication. It’s difficult to know which came first in evolution: the ability to hear or the ability to see, but fish are thought to have developed vibration-sensitive hairs hundreds of millions of years ago, before they could see. The fancy three-boned middle ear of mammals is—along with mammary glands—our defining trait. In the womb, we can hear before we can see. By birth, hearing is our most fully developed sense. Because sound waves vibrate through bones and the brain (the frequency of a violin note, for example, will cause neurons in the auditory cortex to fire at exactly that frequency) it is a sense we feel with our whole being.

It’s only after sound signals wash through our limbic brains that the frontal cortex gets to weigh in, for example interpreting the big rumbles as a familiar DC-10, not a marauding lion. In the microseconds in between, though, a stress response has already begun. If, as Stanford neuroscientist Robert Sapolsky points out, lots of microstresses administered in a slow drip over time add up to chronic stress, then even something as harmless as airplanes heard during sleep can accrue in the stress bank.

Epidemiological and case-control studies overwhelmingly back up this observation. Many have been carried out in Europe, where high-density neighborhoods surround busy airports and where excellent health records are easy for researchers to access. In a study of 2,000 men over age 40, environmental noise above 50 decibels was associated with a 20 percent increase in hypertension. In another study of 4,800 adults over age 45, every 10-decibel increase in nighttime noise was linked to a 14 percent rise in hypertension. Health experts studying nearly a million people living near the Bonn airport found that women living with noise over 46 decibels were twice as likely to be on medication for hypertension as those living with levels under 46 decibels. The World Health Organization attributes thousands of deaths per year in Europe to heart attack and stroke caused by high levels of background noise.

Researchers followed hundreds of children over two years before and after an international airport opened in Munich. They also looked at a control group of similar children who did not live as close to the airport. The stress hormones epinephrine and norepinephrine nearly doubled in the noisy-hood kids measured at six and eighteen months after the flights began. Their systolic blood pressure went up five points (the quieter-neighborhood kids’ blood pressure went up two points).

In the largest and scariest study to date looking at noise pollution and children’s cognition, funded by the European Union and published in the Lancet in 2005, researchers followed several thousand children attending elementary schools near major airports in the U.K., Spain and the Netherlands. They found significant impacts on reading comprehension, memory and hyperactivity. The results were linear: for every 5-decibel increase in noise, reading scores dropped the equivalent of a two-month delay, so that kids were almost a year behind in neighborhoods that were 20 decibels louder (results were adjusted for income and other factors). There’s something real to the phrase “you can’t hear yourself think.”

As the authors of an important review paper on noise grimly noted: “The different types of stress reactions may . . . exert an adverse influence on the equilibrium of vital body functions. These include cardiovascular parameters such as blood pressure, cardiac function, serum cholesterol, triglycerides, and free fatty acids, hemostatic factors (fibrinogen) impeding the blood flow in terms of increased plasma viscosity . . . and presumably blood sugar concentration as well.”

These health effects are serious. I’m frankly surprised they aren’t better known, and that flight-path real-estate values don’t seem to reflect them, at least not in D.C. After reading the studies, I loaded a decibel meter app on my phone. To my children’s amusement, I’ve taken to running around and measuring the noise levels in and out of the house. Distressingly, they are comparable to levels associated with hypertension and learning delays in the studies I’ve been reading. I asked for noise-canceling headphones for Christmas, and I often wear them while working at home. Reagan National limits flights at night, but many international airports around the world don’t. Technology offers some hope: jets have grown quieter in recent years and even muffled helicopters are being developed. Every decibel matters.

Interestingly, the researchers describe another outcome of hearing these noises: annoyance. It doesn’t sound very scientific, but it turns out to play a big role in how people respond to noise, and therefore, stress. It’s a simple concept: the more annoyed you are by the planes/trains/trucks, the worse you feel. Stress is not just a physiological response; it’s a response that can be mediated by attitude or what psychologists sometimes call framing. This is why the adrenaline of skiing off a ledge into a steep chute can fill some people with energy, euphoria and focus and others with knee-buckling terror.

I realize this doesn’t bode well for me regarding the airplanes, since I go out of my way to shake my fists at them. I just hope I don’t become like eighty-two-year-old Frank Parduski, called “the world’s first anti-noise martyr” by New Scientist magazine after he was run over by a motorcyclist he was harassing in order to get him to quiet down his two-stroke steed. But when visitors to national parks are told the loud airplanes overhead are part of important military exercises, many report being less disturbed by them. It’s a good trick if you don’t mind a dose of propaganda with your nature. It’s not a plane; it’s patriotism.

There’s some evidence that more introverted or neurotic people are more annoyed by loud noises. They also may be less likely to become habituated to them. On the other hand, the louder and more intrusive the noise, the more likely you will grow annoyed. There’s a bit of a chicken and egg problem. And whether you like planes or not, your brain still has to work hard to ignore them, and nobody can entirely Zen their way out of that.

THE U.S. NATIONAL PARK SERVICE is uncommonly interested in noise pollution because it operates under a federal mandate to protect its resources, including, since 2000, natural soundscapes. It’s practically an impossible task, but as bioacoustical scientist Kurt Fristrup points out, a little bit of noise regulation can go a long way. Fristrup coordinates the science at the rather romantic-sounding “Natural Sounds and Night Skies” division of the agency. I imagine the staff running around wearing geeky headphones and glow-in-the-dark tee shirts depicting their favorite quasars. Fristrup’s research agenda includes not only documenting the ill effects of anthropogenic noise on visitors and wildlife, but also documenting the beneficial effects of its absence: Why should we save the sounds of nature? What do they do for us? Fristrup is an accidental sound guy; he intended to study biomedical engineering at Harvard but got waylaid by paleontologist Stephen Jay Gould and evolutionary biologist E. O. Wilson. Biophilia rubbed off. Now he applies engineering to concepts of evolution, survival and ecosystem health. “We all interact with our environment through our senses,” he told me, “so any pollution not only affects the fabric of our lives but our connections to everything else.”

To learn more about how sound changes our brains and to find out just how noise-sensitive I am, I ventured to the sound labs of Pennsylvania State University. I was met by Peter Newman and Derrick Taff, two young park-rangers-turned-social-scientists in the Department of Recreation, Park and Tourism Management who work with Fristrup’s group. Newman also didn’t start out studying sound, he explained to me as we navigated a noisy cafeteria on campus. He was interested in parks and crowds, and was conducting visitor surveys at Muir Woods National Monument, known for its ancient redwoods.

“We asked if there was one thing to fix about the park unit, what would it be?” he explained. “And people said they wished it were more quiet. I was surprised what a big deal it was, but these were old-growth trees with a primeval feel, and visitors felt it should be quiet. Later we went back and analyzed the words they used, and they were so emotion-laden. Words like ‘soothing,’ ‘peaceful.’ That was interesting to us. That’s where the research started dipping its toes into health.” (And the survey carried weight: Muir Woods now has a “quiet zone,” like the Amtrak quiet car: no phones, soft voices. It reduced the background noise there by three decibels, which is enough to double the listening area. So instead of hearing birds something like 10 yards in front of you, now you can hear them 20 yards away. That’s a lot more birds.)

Now Newman and Taff run experiments out of the university’s Acoustics Social Science Lab, the acronym of which, people noticed, resembles asshole, so they’re switching the name around. Among other things, Newman and Taff and their colleagues have discovered that human-caused noise actually makes parks look worse, not just sound worse. Visitors hearing loud vehicle noise rate parks as 38 percent less scenic than those who don’t hear it (and motorcycle sounds had the most impact, followed by snowmobiles and propeller planes). Counterintuitively, the soundscape was affecting the viewscape. Just imagine all the beauty we’re missing out on. (Opposite effects are seen in cities, when people rate urban settings as more attractive when they can hear birdsong.)

Veering into human health, Newman and Taff decided to team up with Joshua Smyth, a biobehavioral health psychologist also at Penn State. He’s interested less in how sound messes with your psyche and more interested in how it can make you feel better. Can some sounds be an intervention or an antidote for stress and depression? This appeals to Newman and Taff because natural sound is a resource the parks need to save before it’s too late. If it’s good for you, they want to know. They were familiar with the literature on nature as psychologically restorative, and it seemed to them that sound was a potentially powerful but underappreciated component of nature.

To tease out the sound piece, and to see how it worked for me, Smyth ran me through his current experiment. First he hooked me up to a heart rate monitor, which I would wear throughout. Then he gave me the Weinstein Noise Sensitivity Scale test, which asked a bunch of questions about my attitudes to various types of noise from things like a stereo to street traffic. I scored a 5.2. Adults average a 4, and college students average a 3.5, which puts me in the 88th percentile of sensitivity to noise. No surprise there. But in a short personality test, I emerged as not too neurotic, and of medium agreeableness (and no doubt more neurotic and less agreeable since moving to D.C.).

Next, I spit into a test tube to provide a reading of my pretest cortisol levels. Now the real fun would begin. In order to tell if nature sounds help “restore” subjects psychologically, Smyth has to first stress them out. Public speaking and math tests are two of the most dreaded tasks shared by a large number of people. So I was handed a pen and some paper and told to prepare a short speech about why I should be hired for my dream job. Partway through, my notes were abruptly taken away from me and I was told to stand and deliver the speech to a large mirror, behind which sat a panel of faceless judges. Several times during the 5-minute speech, I was interrupted and told to speak up. As I later discovered, this gauntlet of misery is called the Trier Social Stress Test (and it often includes a mental math component, typically repeatedly subtracting a number like 13 from a four-digit number). I figured Trier must be some sadist who devoted his life to freaking people out, but it turns out the test is named for Germany’s University of Trier, where the test was formulated in 1993. It works: even though I knew there was no “panel of judges,” I still showed a textbook response, with my heart rate climbing from the mid-60s to the mid-90s during the speech, and my cortisol levels (as revealed later) rising from 6.7 nanomoles per liter to 12.1. It’s reductive to call cortisol a stress hormone, but lower levels generally mean lower stress. Researchers tussle over how reliable a measure this is (cortisol naturally varies over the course of the day, as well as during the menstrual cycle, so researchers often use it to study men).

Next, Smyth randomly assigns subjects to one of three recovery exercises: watching a fifteen-minute nature video with nature sounds, watching a fifteen-minute nature video with nature sounds and motorized sounds, or just sitting in a quiet room with no video. My video started playing, a simple scene from Yosemite of a summer meadow, some chirping birds, a blue sky. But a couple of minutes in, I heard a truck engine, followed by quiet, followed by the sound of a propeller plane. I’d been assigned to the second condition, and I again displayed a textbook response: once the nature video started, my heart rate immediately sank to baseline mid-60s range. When the truck rumbled, however, my heart rate shot up ten points. It took a while for it to drop again, but after more quiet nature, it plummeted down to the mid-50s. Now I was so relaxed I was practically dead. When noise #2 appeared, my heart rate shot back up, though not as high as the first time. My cortisol levels from this part of the experiment, at 8.2, reflected this almost-but-not-quite restored state (remember, my original level was 6.7 and my speech level was 12.1).

Smyth was also recording my heart-rate variability (HRV), which is fast becoming the darling of physiological stress measurements. It’s increasingly used by scientists, medical doctors and athletic coaches. My HRV had also been monitored in Korea before and after hiking to tell me I had thickening veins. HRV is complicated to understand, especially in translation. It essentially measures—in real time—how quickly your autonomic nervous system responds to and recovers from microevents in the environment. Your heart is like a dancer—when it’s relaxed, it swans up and down with fluidity. That’s high variability, and it’s good. But when you’re stressed, that variability can clench into a much narrower range, the dancer getting a cramp. Some people have chronically low HRV, which is linked to a bunch of stress-related health outcomes like cardiovascular disease, metabolic disease and early death. During the speech test—and the loud noises—my HRV tightened up.

Noise, at least for me, really is a problem. The test showed that it’s simply harder for someone who is noise-sensitive to fully unwind in an urban environment, regardless of its nice parks and nesting ducks. As Smyth put it: “Your recovery was clearly disrupted by the experience of noise. It set back your recovery with a carryover effect of at least a minute. For you, walking in the park, the benefits of nature may be offset by the noise of planes. Those noises are violating your experience of pleasant views and sound. It’s half as stressful as doing the speech task. Those are aren’t trivial effects.”

Based on his research, Smyth has several recommendations for us sensitive types: try to reduce exposure to irksome noise through headphones, office insulation, etc.; if we can’t do that, try to change our attitude about the noise—maybe by thinking that someday I will be on one of those planes getting the hell out of D.C.—and make an effort to experience positive sounds and quiet places.

“We should think about soundscapes as medicine,” he said. “It’s like a pill. You can prescribe sounds or a walk in the park in much the way we prescribe exercise. Do it twenty minutes a day as a lifetime approach, or you can do it as an acute stress intervention. When you’re stressed, go to a quiet place.”

In fact, Smyth thinks short nature-based interventions like this could help more people more efficiently than many other ones that get more attention, like meditation. “Meditation is getting all the glory. Unjustifiably,” said Smyth. “Seventy percent of people will wash out.” Not everyone likes nature, either, but just about everyone likes the noise to die down, at least occasionally.

THESE DAYS WE might worship absolute quiet, but John Ruskin wrote, “No air is sweet that is silent; it is only sweet when full of low currents of under sound—triplets of birds, and murmur and chirps of insects.” To the extent that nature sounds are soothing to most humans, three in particular stand out: wind, water and birds. They are the trifecta of salubrious listening (favorite music and the voices of loved ones are perhaps the happiest of all, engaging almost every part of the brain, according to neuroscientist and musician Daniel Levitin, in This is Your Brain on Music).

Darwin devoted ten pages to birdsong and six to human music in The Descent of Man, noting that both have their origins in sexual selection, the desire to attract mates. As usual, he was correct. The Brits love birds so much that BBC radio broadcasts a daily ninety-second spot of birdsong. British Petroleum gas stations recently began playing birdsong in the bathrooms. “The aim was to create a mental connection with freshness,” said a newspaper report. Good luck with that.

There appears to be something to the “freshness” idea. As British acoustics consultant Julian Treasure put it, birds sing in the morning, and we associate the sound with alertness and safety, a day when all is right with the world. This is how we’ve heard birdsong throughout our evolution. It’s when you don’t hear the birds that something is wrong. Also, birdsong is stochastic, random and nonrepeating, so our brains interpret it not as a language but as a kind of background soundtrack. In fact, birdsong has some uncanny similarities to human-made music, and its range and technical wizardry might, on some unconscious level, stimulate our happy-music neurons. The French avant-garde composer Olivier Messiaen incorporated birdsong into his works and said of birds: “They are our desire for light, for stars, for rainbows, and for jubilant song.”

The brown thrasher can sing 2,000 songs. The cowbird has 40 different notes, and a horny chaffinch might sing half a million times in a season. The Australian lyrebird is the world’s best mimic, and can imitate chainsaws, car alarms and the click of a camera shutter (none of which reflects well on its habitat). The melodic hermit thrush most often sings on a mathematic substrate that follows harmonic intervals in recognizable pitches. The researcher who discovered this is named—I kid you not—Emily Doolittle, a composer at Cornish College of the Arts in Seattle.

Despite the 300 million years that have passed since birds and protomammals split from a common ancestor, our brains are surprisingly similar to the parts of birds’ brains that hear, process and make language. Humans share more genes governing speech with songbirds than we do with other primates. This is because humans and birds coevolved these language centers, both using the same ancient neural hardware, specifically an area called the arcopalladium in birds and the basal ganglia in humans, a region also known for regulating emotion. It’s well recognized that music triggers emotions, but while much has been made of the ability of Mozart to make us weep, tremble and rejoice (largely through the release of dopamine in our mesolimbic reward pathway), birdsong has received far less attention from neuroscientists.

Nevertheless, our doppelgänger birdbrain neurons may help explain our primal affiliation to chirps, trills and tweets. In both birds and humans, the ability to respond emotionally to linguistic and musical sounds became mission critical for mating, communication and survival. The people who named Twitter knew what they were doing. Psych studies using birdsong consistently show improvements in mood and mental alertness. An experiment at an elementary school in Liverpool found that students listening to birdsong were more attentive after lunch than students who didn’t listen. Amsterdam’s Schiphol Airport plays birdsong in a relaxation lounge that also features fake trees. People love it. Treasure, the British consultant, recommends that everyone listen to birdsong at least five minutes a day. I’ve been playing it on an app while writing this chapter. There’s deep snow outside my window, but the spring birds are in full force on my phone. It does feel leavening. And my cat is certainly more awake.

“What I’m trying to do is figure out why it makes people feel better,” said British environmental psychologist Eleanor Ratcliffe. Ratcliffe looked more like a high school student than a scientist. She had long red hair and wore a jean jacket that partially covered up a tattoo of parrots on her left arm. She admitted she was more of a city person than a nature person, but, as she put it, “one doesn’t have to be in nature to be interested in it.” I met her last summer for tea in the courtyard of the Victoria and Albert Museum, an excellent example of a restorative urban space. She opened her laptop, where tracks of birdsong were sandwiched between The Sopranosand a soul mix.

In her lab, she plays birdsong and asks subjects how they feel. “The overarching thing I’m finding is that people perceive bird sounds to be restorative, but it depends on the person, and it depends on the bird.” Not all birds are loved equally. Many people dislike the raspy calls of jays and the brashness of crows and vultures. Ratcliffe launched into a disquisition the way an oenophile speaks of grapes. “Certain acoustic sounds, quiet, high pitch, bright and smooth are more restorative than loud and rough,” she said. “The typical songbird, tweet tweet, the green finch or blackbird, robin, wren, have musical high trills. They are quite complex and melodious. It might help distract people from their troubles, but it’s balanced between distraction and overwork. You want a bird that’s not aggressive but submissive. Magpies are not restorative.”

RATCLIFFE BELIEVES THAT sound can be restorative, and she’s glad it’s finally getting some attention in the research, but it’s likely not the secret weapon of the nature cure. We’re visual creatures, after all, and staring at a wall listening to headphones can take us only so far. Still, the lessons of sound can be translated in useful and creative ways. The city of Phoenix closes iconic South Park to vehicles one day a month for Silent Sunday. When I was in Korea, I’d gone for a walk along the Cheonggyecheon stream. “Stream” is a bit of an overreach. It’s a stream in the way that Orange Julius comes from a tree or the Space Needle reaches space. The Cheonggyecheon used to be a ragtag underground ditch until it was unzipped to the world in 2005 as part of a greening initiative launched by Seoul’s former mayor Lee Myung-Bak. To flesh it out, water is pumped in seven miles from another river and recirculated. Planted trees and flowering shrubs in the stream’s canyon now attract insects and birds. The so-called “daylighting” of canals is one way for cities to make some nature visible again. In Seoul, though, one of its main purposes was to create a new soundscape to compete with the existing one of heavy traffic in the middle of the central business district.

At the entrance, a sleek waterfall drops down a generous story from street level, creating a pleasant rushing sound. At the bottom, I met Hong Jooyoung, a doctoral candidate in architectural acoustics from Hanyang University who specializes in using water sounds to obscure traffic noise. We walked along a good part of the three-mile-long watercourse, dodging other walkers, joggers and picnickers. Some young women were standing around looking at pigeons on the bank. It was a good place to hang out. Among its many benefits, the path here is six degrees cooler than the roadway above in the height of summer. Only about 20 feet wide, the stream often flows over rocks and through reeds. It literally burbles and whooshes, its soothing sounds amplified by the stone walls lining the sunken ribbon of water and path. Hong explained to me that with these new water features, it’s the perception of traffic noise that changes. You can still hear the noise, but you don’t notice it anymore. The traffic here is loud, above 65 decibels, but so is the water. “The creek design maximizes the sound,” he said. “People don’t think of it as noisy because it’s a nice noise. They rate this kind of water sound as most favorable.”

I was reminded of something the National Park Service’s Kurt Fristrup had said, that unless we learn to make cities sound better, we stand at risk of losing the range of this precious sense. He calls our tendency to wear earbuds during all hours of the day “learned deafness.” We are tuning out the real world in favor of our own personal soundscapes. The cost is we forget how to listen. And we lose an opportunity for true mental restoration.

“It’s this gift we are born with, to reach out and hear all these incredible subtle sounds,” he’d said, “and it’s in danger of being lost in a generational amnesia. Some ears will never get a chance to develop sensitivity to those sounds.”

Although Seoul’s creek plan initially drew opposition because of its cost—about $380 million—and the need to reroute an elevated highway, it is now exceedingly popular, visited by thousands every day. The mayor went on to become South Korea’s president.

ON THE LAST morning of my short vacation in Maine, I woke up very early and snuck out of my stepmother’s house while the kids were still sleeping. I donned the EEG cap and slid into a kayak and onto a small lake. One on side sat a rural subdivision, boats and docks; on the other bloomed a generous expanse of the White Mountain National Forest. I paddled through a foot of soft mist resting on the water’s surface. I couldn’t see my blade as it touched the water, but I could hear the drips, and the birds on the approaching far bank. Occasional jets flew overhead, but they seemed very far away. A car started up down at the far end of the lake. Not too bad. It was quite peaceful. I filled my lungs with the mist and the sun and the birdsong, and I regally paddled onward in my proud EEG crown.

The morning’s software algorithm report read like a Trekkie horoscope: “In most people, the alpha rhythm is attenuated when the brain is busy processing and responding to visual stimuli. However, your brain produced substantial alpha even with your eyes open, suggesting that your brain dynamics are governed by long-range cortical connections and that you enter a relaxed state very easily.”

Hah! I got alpha! I’d finally tricked the machine into thinking I was some sort of yogi. For a few moments on a quiet lake, I was.

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