Harmful Effects of Noise

Human brains have evolved to detect and evaluate discrete low volume sounds.  When different birds are singing we tend to focus on one song, perhaps the loudest and the least familiar. We habituate to regularly recurring sounds, tuning them out in favor of detecting novel sounds. The study of natural sounds and the innate tendencies of our mind provides a strong foundation for understanding music on the one had and noise on the other.

Noise violates all the characteristics of natural sounds. Noise is disturbing and confusing because it is too loud, not discrete, not identifiable, and not informative.

Berglund et al described the adverse effects of noise in a 1999 report form the world health organization. Among the adverse effects, they listed: noise-induced hearing impairment; interference with speech communication; disturbance of rest and sleep; interference with task performance; adverse effects on cognitive functions and behavior and  interference with intended activities.

They described noise annoyance as feelings of displeasure and disturbance associated with physical and mental adverse effects.  Humans recognize some adverse effects of noise and learn to tolerate other effects that cause disturbance and disease in the long term. Humans experience negative emotions when exposed to community noise; they report anger, dissatisfaction, withdrawal, helplessness, depression, anxiety and agitation.

Noise affects social behaviors in complex and sometimes subtle ways. Adverse noise effects are often attributed to other causes. Behavior  is strongly determined by noise; aversion and attempts to reduce noise create a range of behaviors such as closing windows, not using balconies, assaulting noisy neighbors, writing petitions, and complaining to authorities. Noise will trigger unfriendliness, non-participation and may lead to overt aggression.  Chronic noise exposure is a form of oppression that leads to depression

Berglund stated:” It has also been suspected that people are less willing to help, both during exposure to noise and for a period after exposure. Noise above 80 dBA is associated with reduced helping behavior and increased aggression. High-level continuous noise exposures may produce feelings of helplessness in children. The effects of community noise can be evaluated by assessing the extent of annoyance among exposed individuals; or by assessing the disturbance of specific activities, such as reading, watching television and communication. The relationship between annoyance and activity disturbances is not necessarily direct and there are examples of situations where the extent of annoyance is low, despite a high level of activity disturbance. “

Edited by Birgitta Berglund MD , Thomas Lindvall, Dietrich H Schwela. © World Health Organization 1999. http://www.who.int/docstore/peh/noise/guidelines2.html