5.12
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 with noise‐sensitive uses such as residential, schools, and
hospitals. 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 help
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 (overflight of military aircraft, firing of weapons, etc.) may create noises in
higher dB ranges.
Three issues relating to Noise have been identified as
part of this JLUS.
NOI-1 Noise from helicopter operations may cause impacts.
NOI-2 Noise complaints are sometimes received related to
non-AZARNG aircraft.
NOI-3 Noise is generated at Florence Military Reservation.
Key Terms
Ambient noise. Ambient noise is the total noise associated with an existing environment
(built or natural) and usually comprising sounds from many sources, both near and far.
Day‐Night average sound level (DNL). The term 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 by 10 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.
A‐weighted day‐night average sound level (ADNL) decibels are commonly used by the
FAA and DoD to represent aircraft noise levels and C‐weighted day night average sound
level (CDNL) decibels are commonly used by the DoD to represent large arms and
demolitions noise levels.
Decibel (dB). A decibel is the physical unit commonly used to describe noise levels,
describing the amplitude of sound as heard by the human ear.
5-108
Compatibility Assessment