Those aggravating things that go wrong in the day and those irritating things that go bump in the night – disrupting routines and interrupting sleep – all have a cumulative effect on your brain, especially its ability to remember and learn.
As science gains greater insight into the consequences of stress on the brain, the picture that emerges is not a pretty one. A chronic overreaction to stress overloads the brain with powerful hormones that are intended only for short-term duty in emergency situations. Their cumulative effect damages and kills brain cells.
Human infants are all ears. They are very conscious of sound and focus on every word they hear, so they can learn to speak. Loud noises trigger a “startle response” – large movements of the baby’s limbs and torso – even while in the womb. Until 18 months old, infants react strongly to distress sounds from other infants.
Crucial to survival, this instinctual reaction to noise enables us to go from a deep sleep to a quick sprint in a matter of seconds. . . or to do battle with surprising strength. Today, however, our stress response is getting knee-jerked around by all the bells and whistles of modern civilization. From the clatter and jar of diesels and dump trucks, to chest-thumping teenage car tunes, noise is almost impossible to block. It’s very uncontrollable and further adds to the stressful impact.
Sudden Death from Noise
A disorder of the heart’s electrical system, known as the Long QT Syndrome (LQTS), is a life-threatening disorder that can be triggered by a loud noise. In people with LQTS, the electrical recovery of their heart takes longer than normal after each heart beat.
Dr. G. Michael Vincent, an expert in LQTS, says this prolongation “renders patients vulnerable to a very fast, abnormal heart rhythm. . . no blood is pumped out from the heart, and the brain quickly becomes deprived of blood, causing the usual symptoms of sudden loss of consciousness (syncope) and sudden death.”
Acoustic stress – such as awakening because of a loud noise – can trigger an episode. Vincent notes that “symptoms usually occur during physical exertion or emotional excitement like anger, fear, or startle” Common examples of startle events include sudden noise, like sirens, the telephone, and the alarm clock.
LQTS is estimated to cause as many as 3,000 deaths in the U.S. each year – mostly in children and young adults – says Vincent, who founded the Sudden Arrhythmia Death Syndromes Foundation (www.sads.org).
Noise Stress and Brain Function-Study
Stress can exacerbate a number of psychiatric disorders, many of which are associated with the prefrontal cortex (PFC), the area of the brain unique to humans. A Yale University study looked at the effects of noise stress on brain function in monkeys. Results indicate that stress impairs PFC cognitive function through its influence on dopamine, a key neurotransmitter that’s involved in many brain disorders, including ADHD and Parkinson’s disease.
The researchers think that “stress may take the PFC ‘off-line’ to allow more habitual responses . . . to regulate behavior. This mechanism may have survival value, but may often be mal-adaptive in human society, contributing to the vulnerability of the PFC in many neuro-psychiatric disorders.”
Preconscious Response to Noise-Study
Because of the immediate need to respond to noise threats, the conscious mind is bypassed. It may not be fast enough to deal with a situation that could be a matter of life and death.
University College London researchers observed the process using functional MRI brain scans of human test subjects who had been stressed by an unpleasantly loud noise that was combined with visual images. Even when a fearful stimulus was present only at the unconscious level, the threat signal triggered activity in the attention center of the cerebral cortex, where the fear response is then channeled to other parts of the brain that prepare the body in the classic flight or fight reaction.
Lead researcher Jorge Armony said, “It makes perfect sense – you can’t stop and think about certain things, you have to react”.
Responding to Noise We Cannot Hear-Study
Even sounds you can’t hear can have a powerful affect on your nervous system. One example is the “infrasound” in the roar of a tiger.
A tiger’s intimidating roar has the power to paralyze animals. Even experienced human trainers are stunned. “We suspect that this is caused by the low frequencies and loudness of the sound,” says Elizabeth von Muggenthaler, a bioacoustician from the Fauna Communications Research Institute in North Carolina. “Humans can hear frequencies from 20 hertz to 20,000 hertz, but whales, elephants, rhinos, and tigers can produce sounds below 20 hertz.”
The shocking power of a tiger’s roar is one example of how humans react to a sound they cannot detect with their ears. But what about all the noise generated by our modern world – including the multitude of ultrasounds whose frequencies are above 20,000 hertz and beyond our hearing range?
Tiger Sound- Study
In the first study of its kind, von Muggenthaler and her colleagues recorded every growl, hiss, chuff, and roar of 24 tigers at the Carnivore Preservation Trust in Pittsboro, North Carolina, and the Riverbanks Zoological Park in Columbia, South Carolina.
The bio-acousticians found that tigers can create sounds at about 18 hertz, and when tigers roar they can create frequencies significantly below this.
This unheard, low-pitched infrasound can travel long distances – permeating buildings, cutting through dense forests, and even passing through mountains.
Low-Level Noise and Stress-Research
Not just loud or sudden noises provoke a stress response. Chronic low-level noise also negatively influences the brain and behavior. Whether from the road or in the office, low-intensity noise has a subtle yet insidious effect on our health and well-being.
Noise at home or school can affect children’s ability to learn. Compared to kids from quieter neighborhoods, children living near airports or busy highways tend to have lower reading scores and develop language skills more slowly. Psychiatric hospitalizations are higher in noisy communities. Bad moods, lack of concentration, fatigue, and poor work performance can result from continual exposure to unpleasant noise.
According to Dr. Alice H. Suter, an audiologist at the National Institute for Occupational Safety and Health: “Included in noise-related problems are high blood pressure, peptic ulcers, cardiovascular deaths, strokes, suicides, degradation of the immune system, and impairment of learning. Noise is also associated with an increase in aggression and a decrease in cooperation.
Females at Higher Risk from Noise Stress-Study
When children have no control over prolonged exposure to noise, it can lead to “learned helplessness” syndrome – a condition linked to forms of depression and to poverty. “It’s a pretty pervasive phenomenon,” says Evans.
He found that “girls exposed to the traffic noise become less motivated, presumably from the sense of helplessness that can develop from noise they couldn’t control.”
Women respond differently to loud noise, too. A study at Texas A&M University found that “women have a lower threshold to experience noise as stressful,” according to psychologist Dr. Mary W. Meagher. “Our data suggest that women may be more sensitive to noise stress than men.” (While the women in the study were more easily “frightened” by a loud unexpected noise, the men were only more “startled.“)
Chronic Sources of Noise
- Are you feeling stressed but don’t know why?
- Could noise be the problem?
- Are you aware of the chronic sources of noise in your everyday environment?