| Although its presence lingered unaddressed
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| | protect public health and welfare; to set
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| for many years, environmental noise is now
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| | noise emission standards for major sources
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| recognized as a significant health issue.
| |
| | of noise in the environment, including
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| Environmental or ambient noise is unwanted
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| | transportation equipment and facilities,
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| or harmful outdoor sound created by human
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| | construction equipment, and electrical
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| activities, including noise emitted by
| |
| | machinery; and to recommend regulations
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| means of transport - road traffic, rail
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| | for controlling aircraft noise and sonic
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| traffic, air traffic - and from sites of
| |
| | booms. Also in the 1970s, the Occupational
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| industrial activity. From delivery trucks
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| | Safety and Health Administration began to
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| to air conditioners, we are constantly
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| | try to reduce workplace noise. And over
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| bombarded by sounds that go unnoticed for
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| | the past 30 years, the general public has
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| the most part. However, out-of-earshot
| |
| | become increasingly aware of the hazards
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| should not mean out-of-mind. It is
| |
| | of environmental noise, and its ability to
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| precisely these innocuous environmental
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| | combat it on an individual and collective
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| noises that should be sounding an
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| | level.One of the most effective
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| alarm.Those involved with the more obvious
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| | environmental noise abatement technologies
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| noise sources such as airports, shooting
| |
| | to be developed is the noise barrier wall,
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| sports, manufacturing or even musical
| |
| | or sound wall. Sound walls are classified
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| concerts have long known the detrimental
| |
| | as reflective or absorptive. Hard surfaces
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| effect of extreme noise levels on
| |
| | such as masonry or concrete are considered
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| long-term hearing. Only recently, however,
| |
| | to be reflective. This means most of the
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| has environmental noise been thoroughly
| |
| | noise is reflected back towards the noise
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| researched for its affect on our mental
| |
| | source and beyond. A barrier wall such as
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| and physical health - and the findings may
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| | the Sound Fighter(R) LSE 2000 with a
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| surprise you. But to gain a better
| |
| | porous surface material and
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| understanding, one needs a basic education
| |
| | sound-dampening content material is said
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| on what, exactly, noise is.Noise intensity
| |
| | to be absorptive. This means little or no
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| is measured in decibel units. The decibel
| |
| | noise is reflected back towards the source
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| scale is logarithmic; each 10-decibel
| |
| | or elsewhere.Sound walls are performance
|
| increase represents a tenfold increase in
| |
| | rated in two categories: Sound
|
| noise intensity. Human perception of
| |
| | Transmission Class (STC) and Noise
|
| loudness also conforms to a logarithmic
| |
| | Reduction Coefficient (NRC). The STC
|
| scale; a 10-decibel increase is perceived
| |
| | determines the amount of noise energy
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| as roughly a doubling of loudness. Thus,
| |
| | transmitted through the wall material. The
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| 30 decibels is 10 times more intense than
| |
| | NRC determines the amount of energy
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| 20 decibels and sounds twice as loud; 40
| |
| | absorbed by the wall material and the
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| decibels is 100 times more intense than 20
| |
| | amount of energy reflected back towards
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| and sounds 4 times as loud; 80 decibels is
| |
| | the source.Walls having STC ratings of 30
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| 1 million times more intense than 20 and
| |
| | or more means that less than 0.1 percent
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| sounds 64 times as loud. Distance
| |
| | of the noise energy is transmitted through
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| diminishes the effective decibel level
| |
| | the barrier material. Many State
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| reaching the ear. Thus, moderate auto
| |
| | Department of Transportation
|
| traffic at a distance of 100 ft (30 m)
| |
| | specifications require minimum STC ratings
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| rates about 50 decibels. To a driver with
| |
| | of 24.NRC measures the amount of sound
|
| a car window open or a pedestrian on the
| |
| | energy absorbed and measures the amount of
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| sidewalk, the same traffic rates about 70
| |
| | sound energy reflected back towards the
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| decibels; that is, it sounds 4 times
| |
| | source. NRC ratings will range between 0
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| louder. At a distance of 2,000 ft (600 m),
| |
| | (100% reflective) to 1 (100% absorptive).
|
| the noise of a jet takeoff reaches about
| |
| | A wall with an NRC rating of .85 means the
|
| 110 decibels-approximately the same as an
| |
| | wall absorbs 85% of the noise and reflects
|
| automobile horn only 3 ft (1 m) away.
| |
| | 15% of the noise back towards the source.
|
| ¹Subjected to 45 decibels of noise, the
| |
| | NRC ratings equal to or greater than .85
|
| average person cannot sleep. At 120
| |
| | are considered to be good sound absorbers
|
| decibels the ear registers pain, but
| |
| | and are often used as the minimum
|
| hearing damage begins at a much lower
| |
| | requirement when considering absorptive
|
| level, about 85 decibels. The duration of
| |
| | walls.A good sound wall is a
|
| the exposure is also important. There is
| |
| | sound-absorbing wall with a STC rating of
|
| evidence that among young Americans
| |
| | 30 or more and a minimum NRC rating of
|
| hearing sensitivity is decreasing year by
| |
| | .8.Is a sound wall the best mitigation
|
| year because of exposure to noise,
| |
| | option for every application? Certainly
|
| including excessively amplified music.
| |
| | not. There are effective mitigation tools
|
| Apart from hearing loss, such noise can
| |
| | for any situation - from earplugs to
|
| cause lack of sleep, irritability,
| |
| | ceiling tiles. But for many outdoor
|
| heartburn, indigestion, ulcers, high blood
| |
| | applications such as traffic,
|
| pressure, and possibly heart disease. One
| |
| | manufacturing, compressor and commercial
|
| burst of noise, as from a passing truck,
| |
| | retail noise, nothing outperforms a
|
| is known to alter endocrine, neurological,
| |
| | well-engineered and efficient absorptive
|
| and cardiovascular functions in many
| |
| | sound wall.* * *¹ Infoplease,
|
| individuals; prolonged or frequent
| |
| | Copyright © 2000-2006 Pearson Education,
|
| exposure to such noise tends to make the
| |
| | publishing as Infoplease.² H.I.N.S.,
|
| physiological disturbances chronic. In
| |
| | IncMurray Stacy is Vice President of Sound
|
| addition, noise-induced stress creates
| |
| | Fighter Systems, LLC, which has been
|
| severe tension in daily living and
| |
| | researching, designing and manufacturing
|
| contributes to mental illness.¹Does this
| |
| | highly efficient absorptive noise barrier
|
| mean we are doomed to a noise-filled life
| |
| | walls since 1973, making it the oldest
|
| of stress? Fortunately, no. Noise is now
| |
| | established manufacturer of such products
|
| recognized as a controllable problem that
| |
| | in America. Sound Fighter walls have been
|
| can be minimized via varied abatement
| |
| | produced for unique noise mitigation
|
| technologies. In the United States the
| |
| | applications around the world, and several
|
| Noise Control Act of 1972 empowered the
| |
| | of the company's walls are in their 30th
|
| Environmental Protection Agency to
| |
| | year of effective service.
|
| determine the limits of noise required to
| |
| |
|
