An impulsive noise exposure model for outdoor military shooting ranges was created. The inputs to the model included spatial interpolation of noise exposure metrics measured from a single round of fire from a small-arms ballistic weapon. Energies from this single-shot model were spatially translated and summed to simulate multiple shooters firing multiple rounds based on the equal energy hypothesis for damage risk assessment. A validation measurement was performed, and the uncertainties associated with measurement and modeling were shown to be acceptably low. This model can predict and assess total exposures and protection measures for shooters, instructors, and other range personnel.
This paper describes a study conducted at U.S. Marine Corps Base Quantico to determine firing range impulse noise levels and assess noise exposures. Measurements were performed with M16 rifles at an outdoor firing range using a 113-channel array of 6.35 and 3.18 mm microphones that spanned potential locations for both shooters and instructors. Data were acquired using 24-bit cards at a sampling rate of 204.8 kHz. Single weapon measurements were made with and without an occupied range, with a shooter and with a remotely triggered gun stand. In addition, measurements were made with multiple shooters to simulate exposures for a realistic range environment. Results are shown for the various range configurations as a function of angle and distance. Analyses include waveforms, spectra, and peak levels, as well as the 100 ms A-weighted equivalent levels required by military standard MIL-STD-1474E. [Sponsored by US Office of Naval Research.]
This paper describes the development of spatial maps for both peak and A-weighted equivalent sound levels from various firearms, as measured with different spatial resolutions. Two outdoor datasets that adhered to the MIL-STD-1474E weapon noise measurement standard are considered. First is an extensive measurement of the M16A4 rifle at U.S. Marine Corps Base Quantico that included several shooter configurations and a circular measurement arc with 15-deg spacing and 3.67 m radius [R. D. Rasband et al., J. Acoust. Soc. Am. 143, 1935 (2018)]. Second is a measurement of many different firearms using an array with 30-deg spacing and 3.0 m radius, performed in Rudyard Michigan [W.J. Murphy et al., J. Acoust. Soc. Am. 132, 1905 (2012)]. Using these levels and conservative estimates based on spherical spreading and symmetry, level maps are created based on shooter position, weapon used, and number of shots fired. The fidelity of the extrapolation procedure and possible future improvements is discussed. [Work supported by ONR, WTB Quantico, and AFRL through ORISE.]
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