Noise ( NOI )
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 using 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 .
Community Noise Equivalent Level . Community Noise Equivalent Level ( CNEL ) is a weighted average of noise level over time . CNEL is the average sound level over a 24‐hour period , with a penalty of 5 dB added between 7:00 p . m . and 10:00 p . m . and a penalty of 10 dB added for the nighttime hours of 10:00 p . m . to 7:00 a . m . by 10 dB . This weighting reflects the added intr disturbance potential of nighttime noise events community background noise typically decrease
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 measured 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
NOISEMAP Program . The Department of Defen on NOISEMAP technology , using linear acoustic formulation to determine the impact of noise .
Sensitive Land Uses . In terms of compatibility uses are uses that are susceptible to , and effect noise , dust and air pollution . Sensitive land use areas , hospitals , convalescent homes and facilit churches , recreational areas , and other similar
Day‐Night Average Sound Level . Day‐Night Average Sound Level ( DNL ) represents an average sound exposure over a 24‐hour period . During the nighttime period ( 10:00 p . m . to 7:00 a . m .), averages are artificially increased
Page 5‐92