Biology Reference
In-Depth Information
The urban soundscape is very heterogeneous in the world but has common
features such as elevated noise level, predominance of low frequencies, diurnal
variation in noise, abundant large flat impervious surfaces, and modified sound
channels, although these characters can be also found in nature (e.g., in streams,
canyons, and windy environments). The same acoustic energy of a metropolitan
area can be found in the great falls (Niagara Falls, for instance), or before the
Southern Hemisphere marine coast (Cape of Good Hope) during a strong wind, or
during Caribbean hurricanes or East Asia typhoons.
6.23 A Historical Perspective of Urban Noise
Noise in urban areas is truly ancient. At the time of the Roman emperors a directive
banned the chariots from crossing the streets of Rome at night to prevent the noise
created by wheels on paving stones. In Medieval Europe, in some cities transit by
chariots and horses was banned at night, or the streets were covered with straw to
reduce the noise and allow residents to sleep.
The framers of the American Constitution in the eighteenth century, working in
Philadelphia, established that covering the nearby cobblestone streets with earth
would avoid reducing their concentration.
In conclusion, noise from roads is an old problem that has persisted across the
centuries despite the improvement of technology and lifestyles. In New York City,
the maximum sound pressure level was measured on subway platforms as 106 dBA
and 112 dBA inside subway cars. In the 10 years from 1980 to 1990 the noise
increased by 10 %, and in 2000 30 % of Americans complaints regarded noise. The
noise was considered so annoying that 40 % of Americans want to change their
place of residence. In New York City in 1998 the noise complaints were at first
place of the Quality of Life Hotline. In 1971 the World Health Organization (WHO)
Working Group announced that noise is a major threat to human well-being.
A technological and useful world demands energy and produces entropic noise
that in the end is considered necessary and regulated. Some activities such as
garbage disposals, dishwashers, clothes washers and dryers, furnaces, refrigerators,
air conditioners, yard maintenance equipment (mechanical shears, chainsaw,
mowing machines) are considered necessary to our life and their sound tolerated.
But we are exposed also to television, radio, and related technologies. The sounds
of internal combustion engines, trains, and ship horns are from necessary devices
that produce a significant dose of noise and require strategic regulation. Noise
from societal purposes, such as emergency vehicles and desired activities, are
tolerated by most people. Ultimately during our life we consider every unwanted
sound to be noise, and noise remains intrusive, pervasive and ubiquitous, and finally
unhealthy.
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