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is important for human health and function (Colten and Altevogt, 2006). Inadequate, interrupted, or poor-quality sleep is associated with a multiplicity of ailments, including
anxiety, obesity, depression, hypertension, diabetes, dementia, and increased mortality (Cappuccio et al., 2010).
The implications for noise control are obvious. Nighttime noise sources, including heating and ventilation equipment; transportation noise; and noise from restaurants, bars, and clubs adjacent to residential neighborhoods, must be reduced to allow high-quality uninterrupted sleep. Horn-based alerts, which can be as loud as 90 dB, should be changed to elec- tronic chirps that can be decreased in volume or turned off altogether. Better sound insulation of walls, roofs, and win- dows will help, but people may prefer to leave the windows open at night. Eliminating or reducing sound at the source is always better than trying to deflect, insulate, or isolate it later.
Forty-Five A-Weighted Decibels Interfere with Human Activity Including Learning
Quiet is necessary for human thought and concentration, which are disrupted at ambient sound levels of 45 dB Ldn. This is best researched in terms of noise interfering with learning (Bronzaft and McCarthy, 1975; Brill et al., 2018) and cogni- tion (Clark and Paunovic, 2018a). High ambient-noise levels also decrease worker productivity and product quality (Ber- glund et al., 1999; Dean, 2019).
Daytime noise must also be reduced. Daytime noise particu- larly impacts those at home during the day, which includes vulnerable populations such as the elderly, children, those too sick to go to work or school, and an increasing percent- age of the workforce working at home at least part of the time. One particularly intrusive urban and suburban noise source is the gas-powered leaf blower (Walker and Banks, 2017). Recent success in banning these in Washington, DC, provides a blueprint for action in other communities (Fallows, 2019) Again, eliminating noise at the source is preferable to increased sound insulation.
Forty-Five Decibel Noise Disrupts Sleep
Single episodes of noise at 45 dB LAmax are loud enough to disrupt sleep (Berglund et al., 1999).
Fifty-Five Decibel Average Daily Noise Exposure Causes Nonauditory Health Effects
At an approximately 55 dB time-weighted average for 24 hours (Lden), noise exposure causes or is associated with a
wide variety of nonauditory health problems including car- diovascular disease (Münzel et al., 2018), obesity (Pyko et al., 2017), diabetes (Dzambhov, 2015), reproductive problems (Ristovska et al., 2014), and mental health disorders (Clark and Paunovic, 2018b). The adverse health effects are small for each individual, but the population health impacts are large because of the large number of people affected by trans- portation noise. A 1 or 2 mmHg increase in systolic blood pressure is unlikely to cause problems in an individual, but if enough individuals are exposed, the average increase in blood pressure will cause some people to have heart failure, heart attacks, or strokes.
There are multiple studies in the European literature on the adverse effects of transportation noise on health. These include road traffic noise (Halonen et al., 2015), railroad noise (Seidler et al., 2016), and aircraft noise (Correia et al., 2013; Basner et al., 2017). Most experts conclude that the data are strong enough to establish causality of transportation noise exposure for the adverse health effects. (Basner, 2016) This body of research supports the recent WHO Environmen- tal Noise Guidelines for the European Region (2018).
Again, the implications for acoustic engineering and design specifications for structures in which people work, live, and sleep are clear: sound transmission coefficients of windows, walls, and roofs must be increased and transportation noise sources must be reduced as much as possible. Effective measures include enforcement of exhaust noise regulations, requiring different combinations of road surface and tire materials, noise barriers (Rochat and Reiter, 2016), changes in aircraft flight patterns, better track and wheel maintenance, and use of rubber rather than wooden or concrete track ties. Other regulatory solutions, such as prohibiting engine brak- ing and restricting airport operating hours, are also feasible.
Sixty A-Weighted Decibel Ambient Noise Is a Disability Rights Issue
The Americans with Disabilities Act (ADA) defines a dis- ability as “a physical or mental impairment that substantially limits one or more major life activities,” with hearing and communicating specified as major life activities (ADA National Network, 2017). People with moderate to severe auditory disorders, including not only hearing loss but also tinnitus and hyperacusis, appear to meet the ADA standard for having disabilities. High ambient-noise levels make it difficult for those with hearing loss to understand speech, worsen tinnitus, and are painful for those with hyperacusis.
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