The sound of silence

Sensory neurons receive input from the outside world and send these signals on to the rest of the nervous system. This makes the concept of ‘silence’ fairly intriguing: what happens when there is very little sensory signal for the rest of the brain to process? It is well known that, after a while, no sensory stimulation means massive hallucinations. But quiet – brief periods of weak or no relevant stimulus – is different:

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 1960s-era notion of “noise pollution,” a name that implicitly refashions transitory noises as toxic and long-lasting.)

Sound waves vibrate the bones of the ear, which transmit movement to the snail-shaped 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. [neuroecology: really? all noises?]

…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…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.

In light of this, I found the experiences of a hermit who has been living alone since the 1980s fascinating:

He explained about the lack of eye contact. “I’m not used to seeing people’s faces,” he said. “There’s too much information there. Aren’t you aware of it? Too much, too fast.” (Note: he may have asperger’s)

“But you must have thought about things,” I said. “About your life, about the human condition.”

Chris became surprisingly introspective. “I did examine myself,” he said. “Solitude did increase my perception. But here’s the tricky thing—when I applied my increased perception to myself, I lost my identity. With no audience, no one to perform for, I was just there. There was no need to define myself; I became irrelevant. The moon was the minute hand, the seasons the hour hand. I didn’t even have a name. I never felt lonely. To put it romantically: I was completely free.”

…”What I miss most,” he eventually continued, “is somewhere between quiet and solitude. What I miss most is stillness.” He said he’d watched for years as a shelf mushroom grew on the trunk of a Douglas fir in his camp. I’d noticed the mushroom when I visited—it was enormous—and he asked me with evident concern if anyone had knocked it down. I assured him it was still there. In the height of summer, he said, he’d sometimes sneak down to the lake at night. “I’d stretch out in the water, float on my back, and look at the stars.”

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