<![CDATA[
<body background="../graphics/niceblue.gif" title="Urban noise, building acoustics, sound city planning." alt="Urban noise, building acoustics, sound in city planning." text="black">
<div align="left">
<font face="Helvetica" size="5"><img height="432" width="292" src="../graphics/noise.jpg" hspace="20" vspace="20" title="Reduce urban noise." alt="Too much urban noise." align="left"></font><br>
</div>
<center>
<div class="Sect">
<h1><b>Urban Acoustics:<nobr><br>
</nobr>Addressing Urban Noise</b></h1>
</div>
</center>
<div align="left">
<p>This document provides basic information by which a lay person can understand noise, its role in the urban environment, and strategies for dealing with it. The technical and strategic framework provided by this document can help individuals and municipalities focus their efforts appropriately as they address urban noise concerns. It should be useful to all urban residents who wish to address noise problems, and to city planners and policy makers searching for ways to increase urban livability by reducing noise. It does not contain enough detail to solve difficult or complex noise problems that require acoustical consultants. However, many noise problems are merely the result of ignorance or carelessness, and can be remedied going forward, often simply and with little expense. Although American policy makers have been notoriously negligent in their duty to reduce noise, with political will, America can readily create quieter cities through sensitive new construction and focused remedial action, assisted by effective noise regulations and enforcement.<br clear="left">
</p>
</div>
<center>
<p><font face="Times New Roman,Georgia,Times" size="4" color="#a7a7b8"><i>Reduce urban noise by sound planning. Plan for acoustics when building cities.</i></font></p>
<div class="Sect">
<h1><nobr><b>Urban Acoustics: </b></nobr><b> <nobr>Addressing Urban Noise</nobr></b></h1>
<p><font size="4" color="black">by Sharon Hudson ©2008-2012</font><font face="Times New Roman,Georgia,Times" size="4" color="#a7a7b8"><i><br>
<br>
</i></font></p>
</div>
<p><a href="../community-info/Urban_Acoustics.pdf" target="_blank" title="Urban acoustics and noise."><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" color="red"><b>Download text without appendices (131 kb PDF)</b></font></a></p>
<p><a href="../community-info/Urban_Acoustics_with_Appendices.pdf" target="_blank" title="Urban noise and acoustics."><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" color="red"><b>Download text with appendices (2.24 mb PDF)</b></font></a></p>
<p><a href="../community-info/Urban_Acoustics_with_Appendices.pdf" target="_blank" title="Urban noise and acoustics."><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" color="red"><br>
<br>
</font></a></p>
<p><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" size="5"><b>Table of Contents</b></font></p>
<p><a href="#community" title="Noise in the community."><b>Noise in the Community</b></a></p>
<p><a href="#sound" title="Basics of noise."><b>The Basics of Sound</b></a></p>
<p><a href="#isolating" title="How to isolate noise."><b>Isolating Sound</b></a></p>
<p><a href="#absorbing" title="How to absorb noise."><b>Absorbing Sound</b></a></p>
<p><a href="#mechanical" title="Low noise mechanical systems."><b>Mechanical Systems</b></a></p>
<p><a href="#acoustics" title="Managing noise for good acoustics."><b>Creating Spaces with Good Acoustics</b></a></p>
<blockquote>
<p><a href="#speech" title="Acoustics for good listening."><b><font face="Times New Roman,Georgia,Times"><i>Acoustics for speech and music</i></font></b></a></p>
<p><a href="#outdoors" title="Reducing outdoor noise."><font face="Times New Roman,Georgia,Times"><i><b>Eliminating noise from outdoor sources</b></i></font></a></p>
</blockquote>
<p><a href="#conclusion" title="We can reduce urban noise."><b>Conclusion</b></a></p>
</center>
<center>
<p><font face="Times New Roman,Georgia,Times" size="4" color="#a7a7b8"><i>Plan for acoustics when building cities. Reduce urban noise by sound planning. </i></font></p>
<h1><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular"><a name="community"></a>Noise in the Community</font></h1>
</center>
<div align="left">
<blockquote>
<blockquote>
<p>"Calling noise a nuisance is like calling smog an inconvenience. Noise must be considered a hazard to the health of people everywhere." --- Dr. William H. Stewart, former Surgeon General of the United States</p>
</blockquote>
</blockquote>
<p>Noise is defined as unwanted sound. The World Health Organization (WHO) <i>Guidelines for Community Noise </i>states:</p>
<blockquote>
<p>"The perception of sounds in day-to-day life is of major importance for human well-being. Communication through speech, sounds from playing children, music, natural sounds in parklands, parks and gardens are all examples of sounds essential for satisfaction in every day life. Conversely, [the adverse effects of unwanted noise include]. . . temporary or long-term lowering of the physical, psychological or social functioning of humans or human organs . . . [including] noise-induced hearing impairment; interference with speech communication; disturbance of rest and sleep; psychophysiological, mental-health and performance effects; effects on residential behaviour and annoyance; as well as interference with intended activities."</p>
</blockquote>
<p>In addition to contributing to hypertension, heart disease, and other chronic illnesses, environmental noise reduces productivity at work, increases the rate of accidents, degrades performance at school, interferes with cognitive development, learning, and reading progress in children, intensifies the development of latent mental disorders, and negatively impacts mental well-being and social behaviors such as aggression and altruism.</p>
<blockquote>
<p>"Since 1973, the Department of Housing and Urban Development (HUD) has conducted an Annual Housing Survey for the Census Bureau in which noise has been consistently ranked as a leading cause of neighborhood dissatisfaction. In fact, nearly one-half of the respondents each year have felt that noise was a major neighborhood problem. In the 1975 survey, street noise was mentioned more often than all other unwanted neighborhood conditions. This survey has also shown that aircraft and traffic noise are leading factors in making people want to move from their neighborhoods. Approximately one-third of all the respondents who wished to move because of undesirable neighborhood conditions, did so because of noise" (EPA 1981).</p>
</blockquote>
<p>Recent surveys parallel these findings. The survey concludes that:</p>
<blockquote>
<p>• Freedom from noise exposure is a component of neighborhood satisfaction, and quiet is highly valued.</p>
<p>• Exposure to (non-aircraft and non-highway) noise typical of many urban environments produces widespread annoyance, speech interference, and sleep disturbance.</p>
<p>• There is a strong relationship between exposure level and the proportion of a community highly annoyed by noise. However, lower levels of annoyance, and the number of complaints about noise, are poor predictors of the prevalence of annoyance, because many other factors influence annoyance and complaint levels.</p>
<p>• Population density is an important correlate of noise exposure. However, demographic factors alone are relatively poor predictors of noise annoyance.</p>
</blockquote>
<p>A new approach to noise is necessitated by the "smart growth" policies of increased densification, urban infill, and mixed land use. Higher residential density and larger buildings, mixed with increased business activity, pedestrian activity, evening and night activity, and public transit and traffic activity, increase the need for urban noise abatement. New and higher buildings will not only amplify noise in the urban center, but may also reflect freeway and other traffic noise into neighborhoods that have never experienced it before. Measures should be taken to anticipate and mitigate these effects. Noise also impacts our daily experience of nature by driving insects, songbirds, and other animals from the urban environment---even from wooded open space if it is near a freeway. Likewise, excessive or unpleasant noise reduces the amount of time people want to stay in an area, and may thereby reduce business and community activities. Finally, since noise remains the reason people most often give for wanting to leave their neighborhoods, noise reduction in cities is vital to any "smart growth" strategy to encourage urban living.</p>
<p>Health experts now realize that noise is more than an annoyance; it is toxic just like other environmental pollutants, with significant health consequences. Living in a lively part of town, even by choice, does not reduce a person's susceptibility to the physiological, psychological, and sociological impacts of noise. Studies show that there is no physiological adaptation to noise. Instead, long-term residency in a noisy area increases the need for areas of "escape" from the noisy environment. The various mechanisms people use to avoid noise stress and sensory overstimulation create social detachment, loss of community, and ultimately, higher crime rates. Thus noise pollution is both a public health and social equity issue, and permitting noise to pervade the less affluent parts of town is no more justifiable than allowing industrial pollutants to do so. Since low- and moderate-income people increasingly have no choice but to live in high-density and mixed use areas, social equity demands that we pay special attention to noise pollution in high-density areas.</p>
<p>All people, businesses, industry, and organizations have an obligation to respect the health and comfort of others. The air is part of the shared commons, and offensive and excessive noise in public spaces is detrimental to the public health, welfare, and safety, and contrary to the public interest. Unwanted noise impinges on the right to the quiet enjoyment of one's home. Less obvious are the downstream impacts of noise in destroying community cohesion and ultimately increasing policing budgets. And given the significant health impacts of noise, one must examine the policy of concentrating traffic on designated corridors and then lining the corridors with high-density housing. This not only subjects the most people to the most noise, it also subjects the less wealthy to the most unhealthy environment. It improves the well-being of wealthier neighborhoods, but at the cost of increased health impacts and social inequity.</p>
<p>Solving any environmental noise problem involves four steps:</p>
<blockquote>
<p>• <u>Acknowledging</u> and assigning priority to the problem.</p>
<p>• <u>Quantifying</u> the problem using noise measurements or analytical means.</p>
<p>• <u>Creating</u> regulations based on applicable criteria, goals, and noise limits.</p>
<p>• <u>Abating</u> noise by enforcing regulations to eliminate, reduce, or control the noise.</p>
</blockquote>
</html>
]]>