Environmental Engineering Reference
In-Depth Information
In 2002, the European Union adopted a Directive which set out for its member
nations a community approach to manage and evaluate ambient noise in order to
protect public health [64]. This directive asked the member countries to map noise
especially in their large cities, implement action plans to curb noise based on these
maps, and provide information to the public on the dangers of noise. The Directive
focused on environmental noise and did not deal with noises in the workplace,
between neighbors or from military aircraft. A working group from the EU devel-
oped an inventory of noise mitigation methods, laying out the broad requirements
for a program of noise mitigation at the national level [65].
Legislation or directives will give rise to legal measures that will include stan-
dards to control and monitor noise. One example of this is the federal rule that
allows the creation of quiet zones at railroad grade crossings. Such measures can
be used to create noise maps, identify noise exposure levels in different situations,
establish land use and zoning, develop noise codes for construction, and establish
enforcement measures. Legislation will be largely abetted by existing technology
that can lessen the ambient noise. With legislation providing the “will” to abate
noise, technology will find the “way” to mitigate noise.
4.9.2 The Role of Technology in Noise Mitigation
Mitigation of noise can take place in one of three fundamental ways: at the source,
along the path of transmission between the source and the person who hears the
noise (the receiver), and at the receiver.
4.9.2.1 Noise Mitigation at the Source
Control of noise at the source, it is generally agreed, is the most desirable way to
eliminate environmental noise. Controlling noise at the source involves the appli-
cation of methods and technologies that insulate, absorb, dampen, or isolate the
vibrations that produce sound. During the past thirty years, jet noise in the United
States has decreased about 20 dB, and this has been due to the great emphasis placed
on quieting aircraft engines. However, this past year the rise in fuel prices and the
desire to emit less harmful gases in the environment has speeded up the design of
quieter aircraft. Pratt andWhitney boasted that their new engine will feature a geared
fan that will spin independently of the main turbine which, in turn, will lower fuel
consumption and noise [66]. On August 2, 2008, Port Authority of New York and
New Jersey officials welcomed the inaugural A380 from Emirates Airlines which
boasted better fuel economy and less noise within and outside the cabin; this plane
will generate half the noise of other aircraft at takeoff. Boeing has also announced
that its new airplanes will emit less harmful gases and make less noise, in addition
to consuming less fuel. Thus, the “will” to produce quieter planes was sparked by
the high cost of fuel and the fear of global warming and the technology followed.
Sometimes consumers can push for quieter products and, undoubtedly, pur-
chasers of air conditioners who were not pleased that cooler rooms meant adapting
