Right to Quiet Society Noiseletter
Fall 2014, page 2
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our bodies, turn up the volume on our inner thoughts, and attune our connection to the world. Their findings begin where we might expect: with noise.
The word "noise" comes from a Latin root meaning either queasiness or pain. According to the historian Hillel Schwartz, there’s even a Mesopotamian legend in which the gods grow so angry at the clamour of earthly humans that they go on a killing spree. (City-dwellers with loud neighbors may empathize, though hopefully not too closely.) Dislike of noise has produced some of history’s most eager advocates of silence, as Schwartz explains in his book "Making Noise: From Babel to the Big Bang and Beyond".
In 1859, the British nurse and social reformer Florence Nightingale wrote, "Unnecessary noise is the most cruel absence of care that can be inflicted on sick or well." Every careless clatter or banal bit of banter, Nightingale argued, can be a source of alarm, distress, and loss of sleep for recovering patients. She even quoted a lecture that identified "sudden noises" as a cause of death among sick children. In a loud world, silence sells.
Surprisingly, recent research supports some of Nightingale’s zealous claims. In the mid 20th century, epidemiologists discovered correlations between high blood pressure and chronic noise sources like highways and airports. Later research seemed to link noise to increased rates of sleep loss, heart disease, and tinnitus. (It’s this line of research that hatched the 1960sera notion of "noise pollution," a name that implicitly refashions transitory noises as toxic and longlasting.) Studies of human physiology help explain how an invisible phenomenon can have such a pronounced physical effect.
Sound waves vibrate the bones of the ear, which transmit movement to the snailshaped cochlea. The cochlea converts physical vibrations into electrical signals that the brain receives. The body reacts immediately and powerfully to these signals, even in the middle of deep sleep. Neurophysiological research suggests that noises first activate the amygdalae, clusters of neurons located in the temporal lobes of the brain, associated with memory formation and emotion. The activation prompts an immediate release of stress hormones like cortisol. People who live in consistently loud environments often experience
chronically elevated levels of stress hormones. Just as the whooshing of a hundred individual cars accumulates into an irritating wall of background noise, the physical effects of noise add up.
In 2011, the World Health Organization tried to quantify its health burden in Europe. It concluded that the 340 million residents of western Europe—roughly the same population as that of the United States—annually lost a million years of healthy life because of noise. It even argued that 3,000 heart disease deaths were, at their root, the result of excessive noise. So we like silence for what it doesn’t do—it doesn’t wake, annoy, or kill us—but what does it do? When Florence Nightingale attacked noise as a "cruel absence of care," she also insisted on the converse: Quiet is a part of care, as essential for patients as medication or sanitation. It’s a strange notion, but one that researchers have begun to bear out as true.
Silence first began to appear in scientific research as a control or baseline, against which scientists compare the effects of noise or music. Researchers have mainly studied it by accident, as physician Luciano Bernardi did in a 2006 study of the physiological effects of music. "We didn’t think about the effect of silence," he says. "That was not meant to be studied specifically." He was in for a quiet surprise. Bernardi observed physiological metrics for two dozen test subjects while they listened to six musical tracks. He found that the impacts of music could be read directly in the bloodstream, via changes in blood
pressure, carbon dioxide, and circulation in the brain. (Bernardi and his son are both amateur musicians, and they wanted to explore a shared interest.) "During almost all sorts of music, there was a physiological change compatible with a condition of arousal," he explains.
This effect made sense, given that active listening requires alertness and attention. But the more striking finding appeared between musical tracks. Bernardi and his colleagues discovered that randomly inserted stretches of silence also had a drastic effect, but in the opposite direction. In fact,
two minute silent pauses proved far more relaxing than either "relaxing" music or a longer silence played before the experiment started.
The blank pauses that Bernardi considered irrelevant, in other words, became the most interesting object of study. Silence seemed to be heightened by contrasts, maybe because it gave test subjects a release from careful attention. "Perhaps the arousal is something that concentrates the mind in one direction, so that when there is nothing more arousing, then you have deeper relaxation," he says. In 2006, Bernardi’s paper on the physiological effects of silence was the mostdownloaded research in the journal Heart. One of his key findings - that silence is heightened by contrasts - is reinforced by neurological research.
In 2010, Michael Wehr, who studies sensory processing in the brain at the University of Oregon, observed the brains of mice during short bursts of sound. The onset of a sound prompts a specialized network of neurons in the auditory cortex to light up. But when sounds continue in a relatively constant manner, the neurons largely stop reacting. "What the neurons really do is signal whenever there’s a change," Wehr says. The sudden onset of silence is a type of change too, and this fact led Wehr to a surprise. Before his 2010 study, scientists knew that the brain reacts to the start of silences.
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