Penalties for small arms noise assessment.

Abstract

Proper assessment of the noise created by Army testing and training remains a question that is not fully answered. The most difficult noises to assess are the impulsive noises generated by large weapons, small arms, and helicopters. Currently, general community noise is assessed using the A-frequency weighting and some form of ‘‘energy equivalent’’ level. In the United States, the day–night average sound level is used. For clearly impulsive sound, adjustments or ‘‘penalties’’ are sometimes added to the formulation to account for the increase in annoyance generated by the impulsive character of the sound. One purpose of the present test was to further define and develop adjustments or ‘‘penalties’’ that can be used to assess military noise vis-á-vis normal, urban noises. The study was designed as a paired comparison test where the subjects were presented pairs of sounds and asked, for each pair, which was more annoying, the first or the second sound. The test sounds came from one of three categories of military sources that were: (1) tracked vehicles, (2) small arms fire, or (3) large blasts. The other sound in a pair was one of two control sounds that were: (1) the sound of a wheeled vehicle passing by, or (2) a computer-generated noise. This paper concentrates on small arms noise. The results are for measurements made outdoors−even when the subjects are situated indoors. This is considered to be the proper location since common noise such as traffic is normally assessed on the basis of outdoor levels. The small-arms penalty averages about 8–10 dB across conditions of windows closed or open or subjects outdoors.