Risk of Hearing Loss Injury Caused by Multiple Flash Bangs on a Crowd

Abstract

A flash bang is a non-lethal explosive device that delivers intensely loud bangs and bright lights to suppress potentially dangerous targets. It is usually used in crowd control, hostage rescue and numerous other missions. We construct a model for assessing quantitatively the risk of hearing loss injury caused by multiple flash bangs. The model provides a computational framework for incorporating the effects of the key factors defining the situation and for testing various sub-models for these factors. The proposed model includes 1) uncertainty in the burst point of flash bang mortar, 2) randomness in the dispersion of multiple submunitions after the flash bang mortar burst, 3) decay of acoustic impulse from a single submunition to an individual subject along the ground surface, 4) the effective combined sound exposure level on an individual subject caused by multiple submunitions at various distances from the subject, and 5) randomness in the spatial distribution of subjects in the crowd. With the mathematical model formulated, we seek to characterize the overall effect of flash bang mortar in the form of an effective injury area. We carry out simulations to study the effects of uncertainty and randomness on the risk of hearing loss injury of the crowd. The proposed framework serves as a starting point for a comprehensive assessment of hearing loss injury risk, taking into consideration all realistic and relevant features of flash bang mortar. It also provides a platform for testing and updating component models.

A Two-Parameter Description for the Injury Risk of Flash Bangs with Uncertainty

“…For a crowd of n c subjects uniformly distributed in a circle of diameter d c , we study the injury outcome on the crowd caused by a flash bang mortar with multiple submunitions. Previously, we constructed a comprehensive Monte Carlo model for the crowd injury outcome, simulating the detailed effects of many model parameters [5]. In the current study, we consider the problem of how to summarize a flash bang situation using a properly designed two-parameter model so that the distribution of the random injury outcome can be accurately reconstructed solely based on the two parameters supplied.…”

“…The actually realized burst position is random, affected by the aiming error. There is more randomness in the problem: the dispersion of flash bang submunitions upon the mortar burst is random [5]. In addition, even at a fixed acoustic dose (SELA) reaching the surroundings of a subject, the injury outcome is still random, affected by the uncertainty of dose propagating into the injury site [6], and affected by the biovariability of subjects' individual responses to a given dose at the injury site [7].…”

“…Previously we developed a comprehensive computational framework simulating random realizations of crowd injury outcome in a situation specified by the crowd and flash bang parameters [5]. Some of the parameters are summarized below: , steepness coefficient in the dose-injury function for a hearing loss of 30 dB or more in noise-induced permanent threshold shift (PTS).…”

“…The predicted crowd injury outcome is a mixture of triangle-binomial and uniform-binomial distributions. See text for a description of the 6 panels.The distribution of crowd injury outcome N is fully described by the MonteCarlo computational model with all relevant parameters[5]. For practical field operations, it is desirable to avoid the complexity of the Monte Carlo model, and to do prediction based on a concise description of N using only one or two parameters.…”