Analysis of animal blast overpressure study data to compare current impulse noise criteria and propose some new criteria.

Abstract

The effects of high-intensity impulsive noise on the auditory system are complex and difficult to quantify in a simple criterion. Several impulse noise criteria (e.g., MIL-STD 1474D, Pfander, Smoorenburg, LAeq8hr, and a model-based method called AHAAH) are studied for their analytic structure to understand their underlying basic assumptions. Then, these criteria are compared for their performances based on animal blast overpressure data obtained from 905 chinchillas exposed to 137 exposure conditions. The noise exposures consisted of different impulse sources, peak levels, number of impulses with various temporal spacing, and presentations in reverberant and non-reverberant conditions. The noise data are analyzed using the analytic wavelet transform to study their time-frequency structures in relation to patterns of measured auditory damage of chinchillas. Based on these studies, a few new metrics are proposed by taking advantage of capabilities of the advanced signal analysis tool. The statistical correlations of the new metrics with the chinchillas’ observed auditory damage are compared with the MIL-STD 1474D, Pfander, Smoorenburg, LAeq8hr, and the AHAAH model damage risk criteria. Possibility of developing a new impulse noise standard according to the approach adopted in this study as well as remaining challenges are discussed.