Sounds Wild and Broken, page 35
So far, these differences have led to little genetic divergence between country and city blackbirds. The DNA of city birds tends to be less diverse than that of countryside birds, the mark of recent colonization by a few individuals, a similar signature to that in the genes of animals on oceanic islands. There is also some evidence that genes associated with risk-taking and anxiety are changed among urban blackbirds, although whether and how these subtle shifts in DNA change behaviors is unknown. The Eurasian blackbirds’ transformation in the city seems driven not by genetic evolution, but by evolutionary changes that run parallel to genes. When mother birds provision their eggs with hormones, they shape the singing and behavior of their offspring. It is possible, then, that it is the physiology of egg laying that leads to different songs and other behaviors in the city. Cultural evolution may play a part, as it does in white-crowned sparrows, where the form of song adapts to place through listening, copying, and experimentation by young birds. Last, every individual bird molds its behavior to the moment, changing its song as the soundscape changes, preferentially singing when noise is low. Blackbirds using especially reverberant places to gild their songs are, perhaps, another example of this adaptation. The city provides not only acoustic difficulties but opportunities for sonic enhancement.
In just over one hundred years, some populations of the Eurasian blackbird have transformed themselves into city dwellers. In another century or two, genetic changes may catch up with and reinforce these differences. But just as Haussmann tore down and rebuilt Paris in the nineteenth century, it is likely that the next century will see changes just as radical, pushing the birds’ behavior, physiology, and genetic evolution in new directions. Paris and other cities will continue to heat up, driving out some species and inviting in new ones, including disease-carrying mosquitoes and ticks from the subtropics, some of which may prosper in the heat of the city, turning what is now a refuge from disease into an infectious trap. In the last twenty years, for example, Eurasian blackbirds in Germany have been cut back by 15 percent by the newly arrived Usutu virus from Africa, declines that are more severe in warmer years and locales. Human social demand for heat-mitigating street trees and parks will increase, a trend well underway in most major cities, expanding habitat for tree-loving urban animals. Human population density and resource use will change in unpredictable ways, just as it has for millennia. In the eighteenth century, no naturalist would have predicted that the Paris of the future would be an island of stone and concrete in a sea of leafy suburbs, filled with the song of a forest-specialist bird, a sound modified to fit the city. If blackbirds are present in another century or two, their songs will carry within them the now unknown nature of this future city.
By finding ways to thrive amid streets and parks, blackbirds and other urban colonizers have increased their breeding densities over time. Bird species that first colonized European cities in the 1800s now breed, on average, at densities 30 percent higher than those of their rural cousins, an impressive testament to life’s adaptability. But most wild animals cannot live in the city. In the blackbirds’ songs, I hear flexibility and resilience. My mother, on hearing the same song from a Paris apartment, also heard what was missing, the cadences of dozens of other bird species that she knew from the countryside. Yet the city also helps rural birds. By concentrating human activity, land use, and consumption, urban areas make possible the lives of nonhuman animals elsewhere. Were humanity to abandon its embrace of urban life and spread out more uniformly over the land, ecological calamity would unfold, a great silencing of the voices of other species. This is not a thought experiment. The suburbs have spread humanity’s impact over the land, vastly increasing habitat destruction, energy use, and material needs compared with the “ecological footprint” of people living in cities. When I delight in the dawn chorus in rural woodland, I partly have the efficiency of the city to thank.
About 4 percent of the land surface of the world is urbanized, yet more than half of the human population lives in cities. The human density in the apartment building allows many hectares of forest or field to thrive unencumbered by suburban houses, roads, and lawns. City dwellers also use less fuel, metal, wood, and other material goods that must be mined or cut from the land.
In the blackbirds’ song, I hear an animal finding its place within the city. In the silence around the song is implicit the possibility for ongoing life elsewhere. The city and the countryside live in reciprocity, not only in the human economy, but in the wider community of life.
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Fifty years after my childhood in Paris, I listen from an apartment in New York City. Birds seldom sing on this street, although in the evenings I see night-herons flying over the crowd of apartment buildings, crossing Harlem as they leave their daytime roosts on the Hudson River to feed in the Bronx and East River to the east. The sounds of engines are ubiquitous and, in the hot summer, noise and fumes flow into the apartment through open windows.
As I child, my bedroom faced the street and I was captivated by the work of the éboueurs, bright-vested garbagemen, as they leaped on and off the footplates on the back of grumbling green trucks that seemed to me like hungry mammoths or dinosaurs, urban megafauna. Our apartment was one block back from a busy commercial street, and so noise and bright colors were spikes of stimulation on a street otherwise gentle in its bustle. Now, on a busier street in New York City, these enchantments have faded and life amid the sounds of the city’s physiology—the feeding, blood flow, muscular contractions, and excretions of a huge metal and concrete organism—offer excitements often more trying than enthralling.
At two in the morning, a pickup truck parks under the fourth-floor window, open-doored, its radio cranked. The driver blasts the bus stop with pressurized water, a jet powered by a pump on the truck bed. The hose- down takes ten minutes, but the truck lingers with its speakers thumping for another fifteen. Buses pick up their pace before dawn, hissing brakes and bellowing engines as they stop then pull away onto a steep incline. Windowsills are black with the soot from their engines and those of the hundreds of delivery trucks that pass daily. Garbage trucks arrive just after sunrise to load the van-sized piles of trash from the curbside. Trash bags pound as they are slung into one another, workers shout, and hydraulics whir and gasp: a dawn chorus of plastics and discarded food on their way to landfills. All afternoon, a soft-serve ice-cream truck is parked across the street, its generator an atonal whine and chug, wheezing fumes from an exhaust pipe directed up at apartment windows. The six-lane Henry Hudson Parkway, a traffic artery only parklike in name, and Broadway, especially favored by late-night delivery trucks, undergird these sounds with a permanent drone from their paths just over one hundred meters away. Human voices mix into these sounds, but even the shouts are quiet compared with the engines. After dark, especially on the weekend, family groups pass with speakers on small trolleys, pumping out music on their way to and from this neighborhood’s one small park.
These are mostly the sounds of good work and strong community: a city getting cleaned, public transit running, small businesses finding customers, food and other supplies arriving in the city, and people enjoying time together in public spaces. In aggregate, though, they produce a clamor vigorous and unpredictable enough to disrupt sleep and set nerves on edge. The anxiety twists higher when these wholesome sounds are spiced with occasional jolts of trouble: motorbikes modified to thunder so loud that their midnight passage sets off every car alarm on the block, an argument on the sidewalk that seems ready to tip into violence, or the unsettling crack and jangle of a window breaking.
Noise pollution is a grievance that dates to the first human cities. On clay tablets from Babylonia, in one of the earliest known written stories, we read of the gods’ wrath at our din. Scholar Stephanie Dalley translates cuneiform from 1700 BCE: Ellil, the chief god, complained that the “noise of mankind has become too much. / I am losing sleep over their racket.” To impose quiet on people “as noisy as a bellowing bull,” the gods inflicted disease and famines. They also corrected their earlier omission and assigned a life span to humans, preventing endless population increase. Urban noise, by this account, brought us mortality and the yoke of disease. Perhaps urban scribes kept awake by the voices, music, and clatter of neighbors channeled their frustration into stories of revenge?
At the time these stories were impressed into clay, the global human population numbered fewer than 30 million, and Mesopotamian cities housed tens or hundreds of thousands of people. Now we number more than 7.5 billion, and our cities have populations in the tens of millions. Fifty-five percent of the human population now lives in cities. By 2050, the proportion is projected to be above two-thirds. The soundscape of the city is now the sonic context for most of humanity. Like blackbirds, we have adapted and thrived in this new sonic world but have also suffered.
On the A Line headed downtown from Harlem, four teenagers yell their conversation over the clatter and squeal of the decrepit subway car. One of them shushes the others, but they laugh in her face. “We’re New Yorkers. Loud! That’s what we do. We make noise.” The machinery around them agrees. When I get out at Columbus Circle, I check the reading on a sound meter. Ninety-eight decibels when a through-train passes. These are sound pressures loud enough to damage inner ear hair cells. More than a few hours of exposure can permanently impair hearing. The teenagers’ voices were loud but dwarfed by the power of wheels, brakes, and metal boxes jolting at speed along uneven tracks.
Cities are indeed noisy places, but it is not only loudness that distinguishes their soundscapes. The ambient sound level in many tropical and subtropical forests often approaches or exceeds seventy decibels. Some tropical cicadas are as loud as the subway, blasting at one hundred decibels. The late-summer nighttime chorus of katydids in Tennessee holds steady, for hours, at seventy-five decibels. When visitors from the city come to rural Tennessee in late summer, they complain that they cannot sleep for the insect racket, a reversal of the usual narrative about “noise” in cities and the countryside. A reasonably quiet apartment or office, even in a busy city, is more muted than this, usually between fifty-five and sixty-five decibels. The notion that “nature” is quiet is a product of expectations and experience in northern temperate regions. In Japan, Western Europe, or New England, the forest is indeed much quieter than the city, especially in the colder months of the year when insects, frogs, and birds are soft voiced or absent. The same is true in polar regions or the mountains where quiet reigns in the calm between windstorms. But it is often clamorous in places where plant life abounds and animal diversity is high.
City noise differs most markedly from other soundscapes in its tempi and unpredictable nature. I take a walk across Midtown Manhattan, sound pressure meter in hand. Just south of Columbus Circle, workers are cleaving the street’s concrete. Like surgeons, they incise the skin to reach the arteries and nerves below. Their scalpel is a jackhammer, measuring ninety-four decibels from where I stand on the sidewalk, four meters away. Only two of the crew of five wear hearing protection. A young girl scrunches her face in pain and clamps her palms over her ears as she passes. Adults walk past, unflinching. A block north, a bus lets off its air brakes right as it draws level with me, startling a passing snowy canine puffball so that it jumps forward and yanks on the leash. Two blocks on, construction workers drop a metal pile of scaffolding tubes. The clatter breaks the stoicism of a couple of suited walkers, causing them to twitch, then dart their heads around. An ambulance punches its siren at a double-parked car. Someone shouts in my ear, trying to reach a friend on the other side of the traffic-filled avenue. Apart from the jackhammer that was plainly visible in a closed-off street lane, I could anticipate none of these sounds. Loudness is stressful and sometimes painful, but so, too, is immersion in a soundscape where explosions and poundings arrive seemingly at random. I feel as if I’m walking through a dark space where unseen hands sporadically reach out to slap and shake me.
In places where humans do not dominate, sudden loud sounds are rare and are usually cause for alarm. A tree falling. The sudden appearance of a stealthy predator. The yelp of pain from a bee-stung companion. Each sound stabs us with a surge of adrenaline. But most loud sounds in forests and other ecosystems arrive in more predictable ways and cause no distress. In the rain forest, the raucous cries of toucans and macaws flying in pairs over their vast domains taper in and out as the birds approach then depart. The chorus of cicadas and frogs also waxes and wanes in rhythms that, although sometimes overwhelming in their power, do not arrive as shocks to our ears. Vigorous ocean waves are soothing in their regularity. Even the bang and roar of thunder is usually predictable. We see, feel, or hear the storm approaching. It is the rare thunderclap that comes out of nowhere that is alarming. Now human nervous systems that evolved amid forest and savannah sounds find themselves unprepared for the city. In a day walking around Manhattan, I hear more unexpected bursts of loud sound than my ancestors likely experienced in a lifetime.
City noise—the unwanted, uncontrollable sounds of human activities—has well-known negative effects on our bodies and psyches. Loud sounds can lead to hearing loss, whether the immediate damage caused by jackhammers and other ear busters, or the slow erosion of inner ear hair cells brought on by years of exposure to subway stations, construction noise, or busy traffic. Hearing loss then leads to other problems, such as loss of social connections and an increased likelihood of accidents and falls. Noise not only assaults the hairs in our ears. When unwanted sound hits us, whether from an airplane, passing trucks, or clatter in our homes, blood pressure spikes, even when we are fast asleep. Noise also fragments sleep and increases stress, anger, and exhaustion during waking hours. Our hearts and blood vessels suffer. Heart disease and stroke increase with exposure to noise, likely because chronic exposure steeps us in stress hormones and high blood pressure. City noise can also disrupt levels of fats and sugars in the blood. Children bear an especially high burden because noise disrupts cognitive development. Exposure to chronic aircraft, traffic, or rail noise at schools leads to difficulties with focus, memory, reading, and test performance. Laboratory experiments on unfortunate rats and mice confirm that noise both changes physiology and impairs brain development. Sound’s nature makes it an especially problematic source of distress. Unwanted light is easy to block by closing our eyes or with a curtain. Unwanted smell can usually be barred with a tight-fitting door. Noise, though, moves through solid matter, finding ears that are always open, always listening.
In Western Europe, where these effects have been well studied, the European Environment Agency estimates that noise is second only to fine particulate matter pollution as an environmental cause of illness and premature death, annually causing twelve thousand premature deaths and forty-eight thousand new cases of heart disease. An estimated 6.5 million Western Europeans suffer from chronic sleep disruption and 22 million—1 in 10 people—experience chronic high annoyance from noise. Few other regions have measured these effects with as much precision, but the costs of noise may be even more severe elsewhere than in Europe. Measurements of noise in African cities, for example, often exceed European urban sound levels. Extrapolating from the European data—admittedly a coarse approximation—suggests that, worldwide, noise in cities likely degrades the health and quality of life of hundreds of millions of people, and annually kills hundreds of thousands. In general, these effects are worsening as roads and skies get busier and industrial activities expand. For example, between 1978 and 2008, air transport quadrupled, a trend that continued until the COVID-19 pandemic.
The burden of city noise is unequally shared. Sound pollution in cities is a form of injustice. Yet we are also a species that loves the soundscape of home. We not only adapt to and tolerate city noise, sometimes we bond to it as a signature of culture and place, the sonic vibe of our neighborhoods. City sounds, then, can paradoxically be both alienating and welcoming, sources of harm and of belonging.
After a summer staying in a friend’s sublet in West Harlem, I move for a few weeks to another apartment, across the East River in Park Slope, Brooklyn. At this apartment, no expressway runs meters from the window. More than two hundred hectares of woodlands, lawns, and lakes in Prospect Park are minutes away on foot. Ice-cream vendors do not park all afternoon under our apartment windows. The buses in this new neighborhood run quiet and clean. I’ve ridden dozens of bus lines in New York City over the last twenty years, but until I arrived in Park Slope I had never ridden one that pulls away from the curb with a gentle sigh and unsmoky exhale, carrying its passengers on a WiFi-enabled glide. West Harlem is a mostly Latino and Black community; Park Slope is majority white, with double the median household income. More than 80 percent of homes in West Harlem are rentals, compared with just over 60 percent in Park Slope.
The unjust distribution of the harmful dimensions of city sound is the sensory manifestation of both the history of city planning and present-day policies. The expressways that run through many New York neighborhoods were routed deliberately to raze and fragment minority and low-income areas, displacing many people and, for residents who remained, increasing noise and air pollution. Robert Moses, the overlord of much of this work in New York, viewed such work as doubly beneficial, connecting mostly white suburbs to the city and destroying, in his words, “ghettos” and “slums.” Moses’s transformation of the city into a hub for private car traffic from outlying areas was repeated throughout the United States, underwritten by a 90 percent cost share from the federal government for urban freeway projects. By the late 1960s, so many minority neighborhoods had been ruined by the slash of freeways that activists pushed back. “No more white highways through black bedrooms” was one of their slogans.
