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The intensity of sound can be mapped. Maps showing
how loud a single noise was experienced over a geographic
area can be made. This type of map would be made by
contouring measured or estimated noise levels over
the area where the sound was experienced.
Maps of airport noise are frequently prepared.
The map above illustrates a measure of sound mapping
know as DNL (day-night average sound level) for the
area surrounding the Sky Harbor International Airport.
It is a graphic illustration of noise levels from
jet traffic superimposed on a city street map. DNL
is the FAA's standard measure for determining cumulative
exposure to noise. It is the average sound level in
decibels over a 24-hour period with a 10 decibel penalty
for noise occurring at night between 10:00 p.m. and
7:00 a.m.
Airport noise mapping is used to identify areas
where assistance with noise control are needed. Many
airports offer programs to replaces doors and windows
in residences, install additional insulation or make
other sound mitigating changes.
The Airport
Noise Map above is from the City of Phoenix website.
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