Is one man’s noise another man’s music?
Noise is considered a type of pollution because it is an unwanted stimulus that intrudes into a person’s environment, but it is quite difficult to define in any objective way. Definitions are invariably subjective because noise is a sound that a person does not want to hear (Evans & Stecker, 2004).
Some research suggests that the subjective experience of noise (i.e., annoyance), not the level of noise itself, is the important factor regarding people’s health (Nivision & Endresen, 1993). Much research has examined chronic noise exposure (defined objectively as a critical level of decibel) in relatively large samples.
However, the effects of noise are also influenced by other factors such as personality and meaningfulness of the noise (Cohen et al., 1986). Babisch and colleagues (2013) emphasize that noise annoyance is largely determined by noise level, so both factors are not independent of one another.
Do we “get used to” noise?
Subjective reports show that people begin to sleep better as they get used to traffic noise, which reflects a so-called habituation process. However, objective polygraphic examinations of people’s brains do not reveal any changes as people begin to “get used to” noise (Kuroiwa et al., 2002; Xin et al., 2000).
In fact, noise exposure may sometimes lead to increased sensitization to noise (Nivison & Endresen, 1993). It seems that some individuals habituate to noise, while others do not. How people adapt seems to depend on people’s sensitivity or personality (Kawada, 2011).
Predictability and the possibility of controlling unwanted noise has been found to reduce cognitive after-effects of noise exposure (Glass & Singer, 1972). Indeed, stress experiments have demonstrated that control is an important factor in moderating one’s physiological stress reactions (Babisch, 2001).
Noise affects us via two distinct routes
The noise reaction model proposes that noise activates the human organism via a direct and an indirect route. The direct route is determined by the immediate interaction of the acoustic nerve with different structures of the central nervous system, which in turn increases physiological stress.
The indirect route refers to the cognitive perception of noise, and it is linked to an increase in emotional stress. Both routes activate the autonomic nervous system and the endocrine system, and a long-term overactivation of these systems may have adverse health effects (Babisch et al., 2013).
Many of us live in noisy environments and seem to do fine, but how does noise exposure in fact affect us physically as well as psychologically. What does research tell us? In this article, I present six unfortunate ways that noise affects us.
6 ways traffic noise affects people
1. Cognitive functioning
Stansfeld and colleagues (2005) examined how aircraft and road traffic noise influenced almost 3,000 children’s cognition and health. The study was cross-national with participants from both the Netherlands, Spain and UK.
The authors found a linear exposure-effect association between chronic exposure to aircraft noise at school (not traffic noise) and impaired reading comprehension and recognition memory in children. Neither aircraft noise nor traffic noise affected sustained attention. In this study, traffic noise did not have a negative impact on children’s cognition. The authors provide a possible explanation:
… sound that shows appreciable variation over time (changing state) impairs cognitive function whereas sound that does not vary (steady state) has little effect. The noise of aircraft flyovers has an unpredictable rise time that might attract attention and distract children from learning tasks. (p. 1948).
One study found that reading scores of children in classrooms near train tracks were lower than scores of children whose classrooms were quieter (Bronzaft & McCarthy, 1975). Another study found that noise affected long-term memory in 9-12 year-old children (Evans et al., 1995).
Yet another study by Tassi and colleagues (2013), involving 20 individuals exposed to daily railway noise and 20 individuals living in quiet environments, found that long-term exposure to railway noise had some unfortunate consequences, reflected by increased reaction times in different cognitive tasks and declines of some parts of the attentional system.
2. Blood pressure
A meta-analysis by Ndrepepa & Twardella (2011) concludes that there is a positive and significant association between noise annoyance from road traffic and the risk of hypertension, and populations of all ages seem to be affected (Chang et al., 2009).
A study by Fuks and colleagues (2010), involving over 4,000 participants, found that traffic noise increased blood pressure significantly. Workplace noise has been found to increase blood pressure as well (Fogari et al., 1994).
3. The autonomic nervous system
A field study by Graham and colleagues (2009) found that higher indoor traffic noise was associated with parasympathetic withdrawal during the second half of the sleep period.
Parasympathetic activation is normally increased during sleep, while sympathetic activation is decreased, which helps restoration of the body. So changes in activity of the autonomic nervous system during sleep may be related to declines in well-being and long-term health. Earlier studies have also reported sympathetic activation to traffic noise during sleep, according to the authors.
Babisch and colleagues (2001) found increased physiological stress in about 800 women, who were exposed to noise during their sleep. The increased physiological arousal was reflected by increases in catecholamines, specifically noradrenaline. Subjective measures of annoyance or disturbance were positively associated with levels of noradrenaline.
Another study by Evans and colleagues (1995) found both higher adrenaline and noradrenaline levels in overnight urine samples from 9-12 year-old children who were exposed to aircraft noise compared to children from less noise exposed areas.
Waye and colleagues (2002) found that workers who were more sensitive to noise showed a higher stress (cortisol) level, and they rated a low-frequency noise as more annoying than workers who were less sensitive to noise.
Previous studies on the effect of aircraft noise exposure at children’s schools have reported an association with more hyperactivity symptoms (Haines et al., 2001; Stansfeld et al., 2009; Crombie et al., 2011).
Tiesler and colleagues (2012) found that higher levels of noise at the children’s homes were associated with an increased hyperactivity/inattention and more emotional symptoms. The authors note that the emotional symptoms may be caused by sleeping problems. The authors also highlight the fact that noise exposure at home was not associated with overall mental health problems, even though it was associated with the above-mentioned symptoms.
Evans and colleagues (1995) even found noise expousre to be linked to a poorer quality of life in children. Another study by Nivision & Endresen (1993) found a strong association between subjective noise annoyance, noise sensitivity and health complaints.
Proper sleep is fundamental to good physiological and mental helth. According to The World Health Organization, In the European Union, 45% of citizens live in areas where environmental night-time noise levels are considered uncomfortable for sleeping, and approximately 30% of citizens are exposed to night-time noise at levels known to cause sleep disturbance (Graham et al., 2009).
Fyhri & Aasvang (2010) found a significant relationship between noise annoyance at night and sleeping problems. Interestingly, exposure to noise in the daytime seems to make subsequent sleep worse (Kawada, 2011).
A cross-sectional study found a moderate and significant exposure-response relationship between nocturnal road traffic noise exposure and sleep quality and problems with sleepiness during daytime (Öhrström et al., 2006). People exposed to chronic railway noise also show more sleepiness during the day (Tassi et al., 2013).
A review by Kawada (2011) emphasizes that noise can cause sleep disturbances. These can be classified into delay of sleep onset, or awakening in the middle of the night, or early morning awakenings. Noise also makes the stages of sleep shallower, reducing the feeling of rejuvenation after sleep. At last, intermittent noise during sleep has more adverse effects than continuous noise (e.g., like aircraft flyovers).