Related to the recent editorial in the American Journal of Public Health, arguing that "secondhand noise" was becoming the counterpart to secondhand smoke in causing real, measurable, health damage, Florence Williams has a fascinating (and disturbing) story in the Jan/Feb 2017 issue of Mother Jones on the effects of noise on cognition and learning ability. Samples:
The world is getting louder. Scientists define "noise" as unwanted sound, and the level of background din from human activities has been doubling roughly every three decades, beating population growth.... This growing anthropophony (a fancy word for the human soundscape) is also contributing to stress-related diseases and early death, especially in and around cities.
By evolutionary necessity, noise triggers a potent stress response. We are more easily startled by unexpected sounds than by objects that come suddenly into our field of vision. Our nervous systems react to noises that are loud and abrupt (gunshots, a backfiring engine), rumbling (airplanes), or whining and chaotic (leaf blowers, coffee grinders) by instructing our bodies to boost the heart rate, breathe less deeply, and release fight-or-flight hormones.
Even if you think you're immune to city noise, it may well be affecting your health. The best research on this comes out of Europe. In one study of 4,861 adults, a 10-decibel increase in nighttime noise was linked to a 14 percent rise in a person's likelihood of being diagnosed with hypertension....
Yet another depressing study examined the cognition of 2,800 students in 89 schools across Europe. Published in The Lancet in 2005, it found that aircraft and road noise had significant impacts on reading comprehension and certain kinds of memory. The results, adjusted for family income, the mother's education, and other confounding factors, were linear. For every five-decibel noise increase, the reading scores of British children dropped by the equivalent of a two-month delay, so that kids in neighborhoods that were 20 decibels louder than average were almost a year behind.
This was no fluke: "To date, over 20 studies have shown a negative effect of environmental noise exposure on children's learning outcomes and cognitive performance," notes a 2013 paper in the Journal of Environmental Psychology. "Studies have demonstrated that children with chronic aircraft, road traffic or rail noise exposure at school have poorer reading ability, memory, and academic performance on national standardised tests." There's science behind the saying "You can't hear yourself think."
Williams goes on to make the obvious environmental-justice point: the neighborhoods likeliest to be very noisy are also exposed to pollutants and hazards of all other sorts. Worth reading in full.