5.18 . Noise
Sound that reaches unwanted levels is referred to as noise . The central issue with noise is the impact , or perceived impact , on people , animals ( wild and domestic ), and general land use compatibility . Exposure to high noise levels can have a significant impact on human activity , health , and safety . The decibel ( dB ) scale is used to quantify sound intensity . To understand the relevance of decibels , a normal conversation often occurs at 60 dB , while an ambulance siren from 100 feet away is about 100 dB . Noise associated with military operations ( arrival / departure of military aircraft , firing of weapons , etc .) may create noises in higher dB ranges .
Key Terms Ambient Noise . The total noise associated with an existing environment ( built or natural ) and usually comprising sounds from many sources , both near and far , is referred to as ambient noise .
Attenuation . Attenuation is a reduction in the level of sound resulting from an object ’ s distance from the noise source or absorption by the surrounding topography , the atmosphere , barriers , construction techniques and materials , and other factors . Sound attenuation in buildings can be achieved through the use of special construction practices that reduce the amount of noise that penetrates the windows , doors , and walls of a building . Sound attenuation measures may be incorporated during initial construction for new buildings or as additional construction for existing buildings .
A‐weighted Decibel ( dBA ). An A‐weighted decibel is a unit of measurement for noise using a logarithmic scale and measured using the A‐weighted sensory network on a noise‐measuring device . An increase or decrease of 10 decibels corresponds to a tenfold increase or decrease in sound energy .
A doubling or halving of sound energy correspo decrease .
Day‐Night Average Sound Level ( DNL ). DNL rep exposure over a 24‐hour period . During the nig 7:00 a . m .), averages are artificially increased by reflects the added intrusiveness and the greate nighttime noise events attributable to the fact t noise typically decreases by 10 dB at night .
Decibel ( dB ). A decibel is the physical unit comm levels . It is a unit for describing the amplitude o human ear .
Noise . Defining noise from a technical perspec energy transmitted by pressure waves in a com More simply stated , sound is what we hear . As levels , this is referred to as noise .
Noise Contour . Noise contours consist of noise connecting points of equal noise level measure a map that fall within that particular dB noise co
Noise Sensitive Receptors / Sensitive Land Use locations and uses typically more sensitive to no areas , hospitals , convalescent homes and facilit churches , recreational areas , and other similar
Slow Route . Slow route refers to an airspace fo 250 knots and between the surface and 1,500 f
June 2017 Background Report