On Looking: Eleven Walks With Expert Eyes (30 page)

I can tolerate the sounds of my son’s cries, but the sounds of other people’s cries, as well as most sounds shared in a city, have made generations of urban dwellers first cringe, then fume, and then, finally, form Quiet Leagues, Anti-Noise Campaigns, and Noise Abatement Commissions. As early as 500 BC there were complaints about the noises of animals working (elephants trumpeting, horses whinnying) and men playing (gongs, drums, or just making merry). By the seventeenth century in London, the complaints began to find their organized center. These afflicted urbanites were subjected to not just babies but also street criers hawking their baskets, beans, bells, cabbage, eggs, or flowers to anyone within earshot. Chimney sweeps, chair menders, and tinkers hollered notice of their services; dogs yelped, roosters awakened, and street musicians added musical insult to auditory injury. Parliamentary action was taken against the musicians and their “devious and hurtful” sounds. By the turn of the twentieth century, New York City had joined the din against the din. The din itself had changed: no longer was the urban soundscape full of noisome animal sounds; machines had overtaken them. The polemics against noise cited the incredible cacophony of engines revving, honkers honking, pneumatic drills, pile drivers, and wheezing trucks. This was on top of the people playing piano poorly inside and saxophone poorly outside. All the singing, crying, rattling, whistling, thudding, slamming, ringing, rasping, and alarming was bad for health and for habitation.

By the time Lehrer and I finally left our position on the corner,
my ears were well nourished, stuffed full. I had almost stopped listening to the city, and that may be why, when Lehrer was saying, “. . . like that siren we heard over there,” I was struck. I had heard no siren. How I could have missed one of the noisiest features of the urban soundscape is beyond me. What Lehrer was describing partially explained it, though: the way the city sounds simply is not the sum total of the sounds in it: “You know, we can’t really record that [siren sound] because if you recorded the siren so far away all this other, closer noise happens,” crowding the sonic scene. “If you record the siren closer, you get a clearly defined sound. But then if you just take that and put it into your soundscape when you’re making an environment, it sounds wrong.”

In the real world, the sound is reverberating in a particular way based on the structures it is passing; the sound arriving at listening ears is changed depending on what lies between the ears and the siren. The pitch and loudness may seem steady, but they are changeable, and they are different if the listener is a block or three away. The Doppler effect will be different based on not just the speed of the ambulance bearing the siren, but on the direction of your movement relative to that ambulance. Viewed this way, every moment of listening in a city is unique, a sonic landscape painted for the moment and then washed away.

Even temperature changes our perception of sound. It is not our ears that are changed, nor the sounds themselves (for the most part), but that different temperatures control how far and where sounds will travel. Perhaps you have a memory, held in your body as much as in your head, of being outside in the wilderness, in a wide open area, the sun beating down on you—and experiencing an intense silence. Or, relatedly, on a clear night outside, hearing distinctly what is going on in a tent three campsites away. Lehrer’s siren carriers farther on the city’s coldest days, when fingers are balled up in mittens and footsteps clop loudly on sidewalks.

We can turn to the sound-making habits of animals to explain what is happening here. Natural selection naturally selects the animals who send signals to their potential mates that can be most clearly received: so, in many cases, evolution favors those who intuitively know how to best send a sound signal through a medium—say, air or water. Not all air (or water) is alike: often it forms a kind of layer cake, in which each layer is at a different temperature or a different pressure. For instance, as you dive deeper into the ocean, the pressure steadily increases: the greater depths have a much higher pressure than the shallower waters. On land, each night the earth cools, and in the morning the radiated heat makes the ground cooler than the sky: here, the lowest layers are cooler than the higher layers. We can think of the layers as having certain “sound speeds”—speeds at which sound can travel.
⁹
It turns out that sound travels more slowly in warmer air (or lower pressure) and faster in cooler air (or higher pressure). If the sound is traveling along a cool layer and there is a warm layer above it, the sound will spread into it and diffuse. On the other hand, if the sound is moving through a warm layer and there is a cool layer nearby, it will continue to travel along that warm layer, which now channels the sound farther before it weakens and fades away.

This is why you will hear the most birds singing at dusk and dawn. After a cold night, when the earth is chilled, the ground layer is cool and the layers above the treetops are warmer: a temperature
inversion from the ordinary arrangement of the ground feeling warmer than the air. A bird singing at dawn can send his tuneful song traveling much farther along the treetops than it otherwise would. This is good news for singing birds, who are hoping to reach as many other bird ears, especially of the female variety, as possible. Likewise, few birds sit around on the ground calling to one another in the middle of a sunny day, and temperature is again the cause. In a warm layer of sound, their calls get scattered every which way. The message they are sending to the bird a skip and a jump away may not even reach them, the sound disappearing into the ether.

Similarly, there is a fine whale radio channel in the ocean—in a layer of ocean. The layer sits at about a thousand meters below sea level in the North Atlantic, where the pressure is not yet too great and the temperature is not too cool. This allows for long-distance sending of sound signals, on the order of miles, channeling the sound horizontally to distant whales’ waiting ears. Some twenty hertz sounds made by fin whales, who live in deep water often under ice fields, are speculated to travel for hundreds of miles. Though these whales are highly social, they are also often quite well dispersed, and make these low-frequency sounds to keep in contact with one another. Their calls could travel even farther but for interference from other sounds made by other whales, the ice itself, or, increasingly, by human beings—from ship traffic, undersea explosions, and Navy sonar.

If sounds travel differently along temperature channels, the seasons of the year could also be considered to be separate channels changing sound perception. After a big snowstorm, the city is noticeably quiet, the snow snatching the din and burying it under its chilly cloak. Packets of snow occasionally flop noiselessly from lamppost heads to the ground below. Few cars roam the street, except the snowplows grittily scraping the asphalt under their wheels. Boots squeak as they carry the weight of bodies over a sidewalk of snow.

My footsteps, quiet in sneakers, were reflecting the spring. We descended the stairs at a subway entrance—the very subway that had rumbled below us earlier. Before Lehrer and I said our good-byes, we lingered in the anteroom of the subway, struck by the sheer number of noises in the space: the clunk of the turnstiles, the snippets of quickly passing conversation, broadcast announcements accompanied by impressive static. When a train actually arrived, it brought its own reverberant broadband rumble, the squeak of its brakes, a swarm of noisemaking commuters, and the whirr of its accelerator. Those entering the station yielded to those leaving, and then the tide turned again. Turnstiles
ding
ed at a prodigious rate, recording the paying fares.

“No one bothered to make that consonant at all,” I reflected, listening to the different turnstile tones overlapping.

“Minor second,” Lehrer responded in a flash, describing what we were hearing. He whistled it. “People don’t like the minor second.”

There is a solid scientific basis for this aversion. The pitch of a sound is its most audible frequency of vibration, but that particular vibration is just one of many produced at the same time with any sound. A note played on a piano, for instance, may be heard as one note, but it “includes” many other pitches that help make up the sound we hear. An experienced musician may be aware
of these pitches; the rest of us are likely not. The series of pitches hidden within one note are called overtones, and they correspond to other notes on the piano. Hit a middle-C and it vibrates at 262 hertz most loudly. But the note at 524 hertz, the C an octave up, rings out as well. This hidden vibration is the first overtone. The fifth, a G, is next, followed by the fourth, the major third, the minor third, and so on. You might not hear these overtones, but you are surely aware of them: an octave sounds pleasing to our ears, as does a fifth or a third. When one gets to the outer borough of the overtone sequence, though, the sounds are more dissonant. The minor second is well in the outer boroughs. Similarly, the tritone, an augmented fourth or diminished fifth, is so dissonant and unnerving that it was thought to be the work of darker powers, and it came to be called
diabolus in musica,
the “devil’s interval.” In the Middle Ages it was prohibited in music.

I wondered if this minor second was having any long-term psychological effect on the transit workers stuck in the underground booths.

 • • • 

One of the old uses of the word
silence
netted and pinned forever to the page in the
Oxford English Dictionary
is the nineteenth-century’s “a want of flavour in distilled spirit.” I thought of this that night as I sat down to listen to the audio recording of my walk with Lehrer. Back in the silence of my office at home . . . wait. There was not silence but
relative
silence. I knew that a few blocks away, a highway hummed. There were regular sounds of apartment living coming out of the back windows my office overlooks. Clothes languidly swished in a warm-water cycle nearby. And the sounds of the day left a ringing in my ears, representing all the sounds we
hadn’t
heard outside. Our brains make sound out of silence.
Noise
seems to be the flavor we are designed for.

As I transcribed the recording I made of our conversation on the walk, I was struck by all the noise the recorder, with its high fidelity and indifferent attention, picked up that I had missed at the time. It captured and preserved its own rhythmic banging against my leg as I strode. It noticed my sniffing, an indication of the chill I was collecting as the walk went on. I was surprised to hear on the tape how often the wind rode in to wash out any other sounds. Once, the curls of a laugh rose above it; other times, it erased everything else. I listened for any extraneous sounds of Lehrer: snapping snaps, sighs, a whistle while he inhaled. He was silent. At the end of the tape, we said our good-byes, and the sounds of the city swallowed him up.

Taking a walk entirely for the purpose of listening, I had still missed many sounds. But something else had happened. What I heard had morphed from noxious urban noise into being the characteristic, flavorful clatter of my city. I enjoyed the roar of traffic and the buzz of flies; I looked at pigeons hoping they would coo; I stared down passersby, silently egging them on to hum or cough. I counted squeals and squeaks and squawks and measured them against whines and whistles. Each sound felt invited, a pleasure. Welcome, sound.

¹
Hertz
(Hz) is the standard measure to describe the pitch at which we hear a sound. Sound is simply a wave of pressure moving through space; the number of hertz indicates the number of those waves per second. The higher the hertz, the higher the sound we hear.

²
And what of giraffes? One might get the idea from children’s literature that giraffes are silent. Not only do they whimper and grunt, but giraffes also emit an infrasonic, low-frequency sound when they “neck stretch,” reaching the neck back over the body, and when tossing their heads up and down.

³
Alas, sometimes one hears less, too: not only does hearing loss occur naturally with age (by this writing I have lost ability to hear the top 6,000 or so hertz of my original hearing range), but it occurs with exposure to any sound at all—even at non–Spinal Tap levels.

⁴
Named for Alexander Graham Bell (his second
l
lost to history) for his role in sending sounds across telephonic wires to waiting ears.

⁵
Among the many reasons to appreciate bats, this one stands out: bats are the primary responsible parties for our not being eaten alive every day by mosquitos.

⁶
I have read, but not heard, that their pulsing rate quadruples with each degree centigrade the mercury rises.

⁷
Ultraviolet light is visible to many other animals. Plenty of bees and birds, for example, use the reflection of ultraviolet light to find food (reflected off a bull’s-eye around the stamen in the center of a flower) or a good mate (whose feathers may reflect more UV light if the animal is healthy).