In Pursuit of Silence (10 page)

All of this poses a question: If we acquired our extraordinary auditory sensitivity—a sensitivity so pronounced that it can detect energy levels one hundred times lower than the energy emitted by a solitary photon in the green wavelength—because the world was striving to be as quiet as possible, what happens now when almost every day we’re exposed to sounds that treat our eardrums like bass drums? Is it possible that the sublime sensitivity of human hearing has become just a point of vulnerability? Will our very sensitivity get clobbered down to where we end up not being able to hear anything at all? Hearing may be the only
one of our five senses that evolved to deal with an ecology, a ratio of sound to silence, the terms of which have been reversed over the course of human history.

The more I learned about hearing, the more unfathomable it seemed that we became loud on purpose.

Why We Are Noisy

On December 28, 1938, a speaker at the American speech teachers’ convention in Cleveland, Ohio, unveiled evidence that their modest profession held the secret to Hitler’s rise to power. In an address before a hushed crowd of fellow instructors, Professor M. D. Steer, director of the Purdue Speech Clinic, revealed his analysis of the German leader’s speeches. Exhibiting pictures of
“Hitler sound waves
,” with lines “zig-zagging sharply and remaining almost constantly in the higher voice level,” Steer showed how Hitler’s voice managed to batter his listeners into “a submissive state bordering closely on hypnotism.” The secret lay in frequency. Steer claimed the typical frequency at which anger was expressed was 220 vibrations; Hitler’s voice clocked in at 228 vibrations. This relentlessly shrill pitch dazed audiences “in much the same fashion as we are stunned by an auto horn.”

It was a bold claim for the scientist from Indiana to make, but not altogether groundless. Hitler himself once remarked that without the loudspeaker he could not have conquered Germany,
and his loud voice was a treasured property of the rising Nazi Party. So essential was its power to the Reich that he even
had a voice double
, one Adolf Wagner, whose sole claim to distinction seems to have been that his voice grew raspy and broke in exactly the same cadences as Hitler’s.
The American National Broadcasting Company
charted the volume of Hitler’s speech to the Reichstag on October 6, 1939, comparing it with that of the speeches by Prime Minister Chamberlain, Premier Daladier, King George, and President Roosevelt on September 3, when Britain and France declared war on Germany. Though the French leader hit some impressive high notes, nobody could compete with Hitler for consistent loudness. Chamberlain’s voice chart looks like a flatlining patient.

If, as the monks believe, we seal our lips in order to draw closer to a higher truth, we shout to acquire earthly clout.

Darwin viewed adult animal vocalization as a weapon. In Darwin’s schema, males make a lot of noise to threaten other males and to seduce potential mates, while females make a racket to indicate their choice of partner for reproduction.
“The sexes of many animals
incessantly call for each other during the breeding-season,” he wrote; “and in not a few cases the male endeavors thus to charm or excite the female. This, indeed, seems to have been the primeval use and means of development of the voice.”

In more recent decades, perhaps in line with our own evolving self-image, the focus of animal research has shifted away from competition toward the use of learned vocalizations in coalition building. In addition to adding nuances to the story of
animal bonding, the expansion of animal-communication studies has led many evolutionary biologists to enlarge the boundaries of the unknown. Birds that use their songs to imitate other birds and animal species are considered especially mysterious.
“What are myna birds
doing in the wild?” Heather Williams, a bird expert at Williams College, said when I questioned her about noise and song production among the feathered flocks. “And parrots? No one understands the vocalizations of parrots in the wild.”

But the dynamic that Darwin focused on more than 125 years ago remains dominant: the intentional emission of sound helps animals secure their niche in a relentlessly competitive environment. And coalition building, for the most part, comes down to finding one’s rank in a group, and assuring oneself of a protective partner in family planning. Perhaps what has changed most is our understanding of the power of sound. It’s now widely accepted that sounds made by males can supplant the need for other physical action against a competitor, while sounds made by females can circumvent the need for making a firm choice among different potential mates. Males willfully maximize perceptions of their fighting prowess through acoustical displays, while females purposefully confuse their listeners with sounds suggesting multiple choices simultaneously. Both of these capacities have been dubbed “diplomacy.” They might also be thought of as a strategic deployment of noise. While silence is often used by an animal to foster invisibility, noise functions as signage for the bodily reality behind it.

Since the late 1970s, Eugene Morton, a zoologist and ornithologist with the National Zoo,
has been constructing sonograms
analyzing the sounds made by a wide array of birds and
mammals. Morton has found a near-perfect correlation between the pitch of a vocalization and its social utility. Low-pitched sounds are equated with aggression, while high-pitched sounds are associated with submissiveness and friendliness. (The cat is the singular, confounding exception to this rule.) A vocalized back and forth between two animals consisting of a bellow and a high-pitched whine might mean the difference between retreat and a clash to the death. The duet becomes its own form of duel.

Long before Bruce Masterton’s contributions, an intuitive understanding of this dynamic was exploited in the commercial sphere. One of the earliest histories of the telephone, by Herbert Casson, a Canadian journalist, published in 1910, describes how the first telephone exchanges were deafeningly loud because the switchboards were staffed entirely by boys who engaged in more or less constant
“cat-and-dog squabble”
with the public, “with every one yelling at the top of his voice.” Then one day someone thought to replace the boys with girls. “The quiet voice, pitched high, the deft fingers … these qualities were precisely what the gentle telephone required in its attendants,” Casson wrote. Girls “did not waste time in retaliatory conversation … and they were much more likely to give ‘the soft answer that turneth away wrath.’ A telephone call under the boy regime meant Bedlam and five minutes; afterwards, under the girl regime, it meant silence and twenty seconds.”

Behind this phenomenon lies the notion of fundamental frequency. Assuming there are no mitigating factors, the frequency of an animal’s vocalization will be inversely related to the size of
its vibrating vocal cords. Even when depth of pitch does not indicate an animal’s size, low-frequency calls often attest to higher testosterone levels. (Testosterone may cause vocal folds to lengthen independently of the rest of the body.) Whether on account of body mass or hormone rush, the deeper the sound, the more threatening the beast. Animals can thus size each other up and determine the advisability of doing battle on the basis of the frequency struck by their opponent.

Among fallow deer, for example, bucks vocalize only during the mating season, producing a call known as a groan.
Researchers from the University of Zurich
have recently shown that the higher-ranking male deer in a herd produce the lowest groans—and that this ranking is also the best predictor of their odds for mating success. Female deer are magnetized by the same acoustic cues indicating dominant status that males rear back from. So important is this call to the future of the deer that at the height of the breeding season a buck will groan up to three thousand times per hour—making them sound more hoarse than a hard-smoking heavy-metal singer after sixty.
At the peak of the rut
, this hoarseness actually raises the pitch of the buck’s call (perhaps also signaling to its rivals a drop in testosterone-fueled fighting spirit).

Although this dynamic, wherein lower pitch indicates greater reproductive viability, holds sway throughout most of the animal kingdom, human noise may be starting to throw a wrench into the works. Studies of certain frog species have indicated that in areas
with significant traffic noise
, male frogs are being forced to raise the pitch of their call in order to make themselves heard. But the calculus for the croakers is tricky since the price of audibility
is a commensurate drop in their appeal to females—and a reduction in their ability to threaten other males. Only by sounding littler and weaker than they actually are can these male frogs get the females to recognize they even exist.

John J. Ohala, professor emeritus of linguistics at the University of California at Berkeley,
has tied the vulnerable submissiveness
associated with higher frequencies to the acoustic origins of the smile. Smiling reduces the resonant cavity of the mouth, thereby raising the vocal pitch of sound emitted. He has also made the case that the larger the vibrating membrane,
“the more likely it is
that secondary vibrations could arise,” giving the voice in question an irregular, rough texture. When a sound includes a number of secondary vibrations, it will be less predictable.
Since we are biologically
programmed to associate unpredictability with danger, a low and rough voice is the most frightening. (It is not coincidental that one of the oldest, most widespread religious artifacts is an
object called a “bull-roarer”
—a piece of wood tied to a string which, when swiftly spun around, produces a loud, roaring, eerie noise. Versions of the bull-roarer have been found everywhere from ancient Greece to Mexico, Africa, Australia, and Ceylon, with its use varying between summoning the gods and chasing off evil spirits.) When I spoke with David Huron, head of the Cognitive and Systematic Musicology Laboratory at Ohio State University, on the subject of the male urge to make loud, deep noises, he said,
“It’s all about pecking order
. That’s why men don’t cry and why the pitch of their voice drops at pubescence.” But what about the fact that acoustical bluster is no guarantee that a physical fight will actually be avoided? “It’s
females who have a low-risk reproductive strategy,” he fired back. “Males have a very low likelihood of contributing to the gene pool.”

By now I had a few ideas about the roots of the pursuit of silence. Our forebears sought quiet to hear threats and potential meals in motion more clearly, and because silence helped them focus. I also could see the way that making loud sounds might, on occasion, have provided a weapon to ward off enemies and attract erotic partners for whom, when it came to vocal cords, size mattered. But still I wondered, is it really true that all our reactions to sound are dictated by simple equations: loud, low sound equals something powerful, so be scared or be prepared to mate, or both; soft, little sound equals something small, so be calm, be prepared to mate, or both? What about noises that stimulate pleasure, pain, or fury apart from nearby mates and predators? How did these fit in with ideas of evolutionary psychology?