Noise Pollution and Cognition

by chw4 min read5th Apr 2021No comments

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Overview

  • Noise stress affects many different cognitive functions, including attention, memory, reaction times, executive function, decision-making.
  • Noise affects productivity.
    • Dean 2020 randomized exposure to engine noise during a textile training course at a government training facility. He found that “an increase of 10 dB reduces productivity by approximately 5%.”
  • Personality type influences how noise affects one’s cognition—introverts are more sensitive to noise. However, when performing low to moderately complex tasks, they may benefit from listening to soft music.
    • Mohammed et al. (2018) showed that extraverts work more quickly in the presence of noise than introverts. Introverts’ levels of attention, tolerance, and focus also decrease more than extroverts when exposed to higher noise levels.
    • Gonzalez and Aiello 2019 show that for people who get bored easily and need more frequent external stimulation, music impairs their cognition. Contrastingly, for people who need low external stimulation, they can benefit from listening to soft music while completing low to moderately complex tasks.
  • Generally, white noise can improve short-term concentration and cognition in specific (e.g. loud/distracting) environments. However, white noise should not be played for extended periods of time.
    • Othman et. al (2019) measured young adults' responses to auditory stimuli when exposed to different background noise levels using an fMRI machine. The study found that auditory and working memory (AWM) was significantly enhanced under a 10 and 5 signal-to-noise (SNR) ratio. (When exposed to an auditory stimuli at 60 dB, the optimal background noise level was around 50-55 dB).
  • In a study of eighty participants, the half of the participants listening to white noise demonstrated superior recall accuracy. White noise may also increase the speed of arithmetic computations and help children with attention deficit disorders.
  • Chronic low levels of noise are detrimental to human health and can damage the auditory region of the brain. These effects have been observed in the 60-70 dB sound pressure level range, which is common among white noise generators.
  • The effects of noises < 70 dB are unclear, but may follow an inverted-U relationship where mild levels of noise can be beneficial depending on the task at hand.
    • (see Othman et. al (2019) above)
    • In a study of white noise’s effects on children’s cognition, the relationship between noise level and performance followed an inverted U shape. However, for highly attentive children (versus moderately or low-attentive children), the relationship between noise level and performance was strictly negative.
    • Mehta et al. (2013) found that moderate levels of noise (70 dB), versus low levels of noise (50dB), enhanced creativity. The study also found an inverted-U relationship between noise and creativity—high levels of noise (85 dB) negatively affected creativity.
  • ~70 dB might be the threshold level for where noise has significant effects on cognition. However, there are still smaller effect sizes below 70 dB.
    • In a study mimicking the effects of coal mining noise, when noise levels reached 70 dB and 80 dB, subjects’ reaction time to acoustic stimuli became significantly longer. Similarly, 70 dB had a significant impact on fatigue levels (measured by flicker fusion frequency).
  • The World Health Organization’s 2011 report, the “Burden of disease from environmental noise,” estimates that “DALYs lost from environmental noise are 61 000 years for ischaemic heart disease, 45,000 years for cognitive impairment of children, 903,000 years for sleep disturbance, 22,000 years for tinnitus and 654,000 years for annoyance in the European Union Member States and other western European countries.”
  • Noise pollution harms heart health. A 2019 study of 500 adults over 5 years found that “every 5-decibel increase in the average 24-hour noise level was associated with a 34% increase in heart attacks, strokes, and other serious heart-related problems.”
  • Noise impairs cognitive development in children.
  • For older individuals, higher environmental noise is correlated with increased risks for dementia and Alzheimer’s.
  • Noise pollution detrimentally detrimentally affects mental health, particularly for individuals with anxiety disorders.

Cognition in adults

  • A study comparing schizophrenic and non-schizophrenic individuals (n=18) found “(i) significant impairments in psychomotor speed, attention, executive function, working memory, immediate and delayed verbal recall and recognition in patients, relative to healthy participants, across all noise conditions, (ii) significantly reduced delayed verbal recall and recognition under both urban and social noise, and (iii) an indecisive response style on a decision making task (Beads) and significantly reduced working memory, in both groups under social noise relative to the quiet condition.”
  • A study of 54 young adults “revealed that mental workload and visual/auditory attention is significantly reduced when the participants are exposed to noise at 95 dBA level (P < 0.05)”

White noise and cognition

  • Studies have found that white noise could slightly improve memory and help adults learn. However, a 2015 review suggested that “white noise has no general effect on cognitive functions. Instead, they indicate differential effects on perception and cognition depending on a variety of factors such as task demands and timing of white noise presentation.”
  • Chronic low levels of noise are detrimental to human health. They “can cause so-called nonauditory effects, such as disturbances of activity, sleep, and communication, which can trigger a number of emotional responses, including annoyance and subsequent stress. Chronic stress in turn is associated with cardiovascular risk factors, comprising increased blood pressure and dyslipidemia, increased blood viscosity and blood glucose, and activation of blood clotting factors, in animal models and humans.” (Munzel et al 2018)
  • Persistent noise from traffic or aircraft have adverse effects on stress, mental health, and cardiovascular function.
  • Long-term exposure to white noise may adversely affect the auditory region of the brain. In rats, long-term exposure to white noise damaged their auditory organization.

Music and cognition

  • The research on this is contradictory and often poor quality. Studies say that music either hinders, helps, or has little effect on cognitive performance. However, most studies don’t control for the type and intensity of the music, the task at hand, or the personality of the participants.
  • The effects of music on cognition depend on one’s personality, the task at hand, and the type of music.
  • Gonzalez and Aiello 2019 show that for people who get bored easily and need more frequent external stimulation, music impairs their cognition. Contrastingly, for people who need low external stimulation, they can benefit from listening to music while completing low to moderately complex tasks. For more complex tasks, “preference for external stimulation significantly and positively predicted word pair scores when there was no music, but did not predict performance when there was music.”
  • Dobbs, Furnham, and McClelland 2011 showed that cognitive performance in silence was better than performance with background music, which in turn was better than performance with background noise.
  • Doulegi 2013 found that performance scores were significantly higher in silence than in all four music conditions, intensity levels, and types of music combined.

Mental health

  • In a literature review of air and noise pollution’s effects on cognition, 3 studies investigating the association of noise and depression showed that “depression was associated with noise levels >70 dB(A), with the noise level of 70 dB(A) being a critical threshold.”
  • Hardoy et al. (2005) found that while anxiety correlated to aircraft noise, major depressive disorder and depressive disorder not otherwise specified were not.
  • Persson et al. (2007) found no significant effect of aircraft noise on the trait anxiety (p = 0.101), however road traffic noise, sounds from neighbors, traffic vibration and sound from other sources were shown to be significantly associated with anxiety.

Noise pollution’s effects on the elderly 

  • A study of elderly adults (>65 years of age) in Chicago found that an increment of 10 A‐weighted decibels (dBA) in noise corresponded to 36% and 29% higher odds of prevalent MCI [mild cognitive impairment] and Alzheimer’s disease. “Noise level was associated with worse global cognitive performance, principally in perceptual speed (–0.09 standard deviation per 10 dBA, 95% CI: –0.16 to –0.03), but not consistently associated with cognitive decline.”

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