The Stark Beauty of Silence

by Justine Wang

We as a society have become accustomed to constant noise. The first thing some will do when they return home is turn on the television. For many of us, either our Pandora or our Spotify playlists provide the background tracks to our studying. If you live in a dorm where the noisy worlds of hundreds of people intersect, you probably cannot remember the last time you experienced sustained quietness. When you finally retreat to the refuge on the fourth floor of Hillman Library, the starkness of the silence can provide not only blessed relief, but perhaps even unsettling discomfort. 

The problem of noise is an inevitable environmental byproduct of communities, especially in urban areas. Noise is an incessant stream of sounds and stimuli from traffic, buildings and, of course, other people. It is rarely seen as more than a nuisance, such as when one is trying to focus or fall asleep, and may only be perceived as harmful in extreme cases leading to hearing loss. However, there now appear to be little known yet substantially detrimental consequences of chronic noise pollution. 

The physiological effects of excessive auditory stimulation on stress hormone levels, high blood pressure and cardiovascular disease have been the subjects of numerous studies. Like many external stressors, noise causes a response in the endocrine system. First, the hypothalamus in the brain signals the adrenal glands above the kidneys to produce cortisol, a stress hormone.  Over time, the cascade of symptoms that arise follows logically from this hormone production, since cortisol constricts blood vessels, leading to higher blood pressure and an increased risk of heart attacks. 

An interesting example of this correlation has been found in Amsterdam, where aircraft noise from Schiphol Airport has been linked to the cardiovascular health of the local community, including a greater quantity of medical treatments for heart ailments and hypertension. In a similar study conducted around Arlanda airport in Stockholm, there was a greater incidence of hypertension among citizens who were exposed to overhead aircraft noise ranging from 55 decibels to over 72 decibels, on par with the noise level of a medium truck or lawn mower. 

In addition to these effects on the body, there have also been studies concerning environmental noise and cognitive abilities in elementary school children. These studies have consistently supported that sustained attention, concentration, long-term memory, speech, reading comprehension and academic performance in young children are stunted by frequent noise from railways, airports and thruway traffic. While correlation does not always suggest causation, researchers have gathered enough evidence to support that noise may likely be the underlying reason for these observations. 

In light of the various adverse effects of noise, the benefits of silence have long been overlooked. In past studies involving auditory stimuli and the brain, silence usually played the role of the control condition, expected to produce little, if any, effect on the overall experiment.  The first discoveries of the effects of silence were thus indirect observations made from studies that were originally focused on the impacts of noise or music.

Fortunately, a 2013 study titled “Is silence golden?” from Duke University was one of the first to break the norm by observing the brains of adult mice as they were exposed to sounds, including white noise, baby mice calls, Mozart piano music and silence for two hours each day over three days. All of these variables, with the exception of white noise, triggered the production of precursor cells in the hippocampus, the region of the brain associated with memory. However, only silence continued to prompt a long-term increase in cell development seven days afterwards. Furthermore, silence also initiated the differentiation of these precursor cells into functioning neurons and facilitated their assimilation into the nervous system. 

This process of creating these new neurons is called neurogenesis, which provides a “draft” or pool from which the newly made neurons can be “recruited” or employed in order to assist in the brain’s response to cognitive challenges. The effects of silence, according to this study, may be especially appealing to college students, as support from new neurons helps our brains learn and memorize information, as well as adapt to unfamiliar situations. 

The ability of silence to promote such a growth of new neurons is an astounding and unexpected discovery. After all, silence has long been presumed to be the absence of stimuli—an idle emptiness that is waiting to be filled. Contrary to our intuition, however, silence is indeed its own unique physiological stimulus. In response to silence, neurons will activate and begin firing in a part of the auditory cortex that is independent of the pathways that process sound. This capacity of our brains to recognize silence is important in understanding speech. It helps us to identify the gaps between words in a conversation, allowing us to distinguish when each word ends and begins. 

For many individuals, silence is often something that must be sought with intention by either putting on our noise-cancelling headphones or finding a quiet haven away from the hustle and bustle of the world. However, recent research suggests that the benefits we can reap from silence are worthy of pursuit.

The amazing connection between silence and neurogenesis inspires remarkable considerations in the field of health care. For example, the decline of neurogenesis in the hippocampus is one characteristic of dementia and depression in adults. If scientists and physicians could refine and harness the power of silence to catalyze the formation of new neurons, it could become a novel treatment supplement for neurological conditions. 

With the sound of silence echoing into the future, lend your ears—it may be worth a listen.