Community Reaction to Impulse Noise: Initial Army Survey.
CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL
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This report gives the results of a noise-impact attitudinal survey done in the Fort BraggFayetteville, NC, area. It shows that to the extent normal sources like airplanes fit an energy model such as the daynight average sound level DNL, impulse noise also fits an energy model. The growth of annoyance levels in a community with increases of loudness occurs similarly for impulse noise and for aircraft and helicopters. The growth of annoyance in a community with increases in the frequency of occurrence of events occurs in a similar way for all noises, except that the integration period for impulse noise apparently extends down to once every few months, whereas annoyance all but dies away for other noises when the frequency of occurrence drops this low. All types of noise sources have roughly the same nighttime noise penalty -- 7 to 10 dB. C-weighting is the best available standard measure a C-weighted DNL CDNL which includes no threshold or impulse correction factor offers the best model to describe community response. To establish an equivalency between CDNL levels used to assess impulse noise and A-weighted DNL ADNL levels used to assess other noise, it is necessary to find a common denominator. It is recommended that the percent of the community highly annoyed in a given noise climate be that common denominator. With this common denominator, about 6 dB must be added to the numerical value of the CDNL level. Author
- Stress Physiology