5.18 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 , which usually comprises sounds from many sources , both near and far .
Attenuation . Reduction in the level of sound resulting from absorption by the surrounding topography , the atmosphere , distance from the source , barriers , construction techniques and materials , and other factors .
Day‐Night Average Sound Level ( DNL ). 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 by 10 decibel ( dB ). This weighting reflects the added intrusiveness and the greater disturbance potential of nighttime noise events attributable to the fact that community background noise typically decreases by 10 dB at night .
Military Training Route . A military training route is a defined airspace that allows for military aircraft to train at high speeds and low altitudes and serves as an awareness tool for non‐participating aircraft that these military aviation activities are occurring in these corridors . The corridor widths can vary and authorize flight at air speeds greater than 250 knots .
Noise contours . Noise contours are made by co noise exposure to form an enclosed area in whi the same . Air Force Instruction 32‐7063 define contours .
Noise‐sensitive uses . Locations and uses typicall including residential uses ; hospitals and medica homes and assisted care facilities ; places of wor educational facilities .
Technical Background Sound is defined as the mechanical energy tran a compressible medium such as air . More simpl hear . As sounds reach unwanted levels , this is r
The central issue of noise is the impact , or perc animals ( wild and domestic ), and general land u to high noise levels can have a negative impact and safety .
Due to the technical nature of this compatibility the JLUS process , this section provides a discuss sound and the modeling process used to evalua following key terms are used to describe noise .
Characteristics of Sound It is important to understand that there is no sin measuring sound , due to variations used by diff conducting sound studies or sound modeling . S various parameters that include the rate of osci ( frequency ), the speed of propagation , and the content ( amplitude ). The sound pressure level common descriptor used to characterize the lou level . The dB scale is used to quantify sound int
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