The uncertainty of engineering grade community noise surveys and predictions relative to two particular variables

Abstract

The uncertainty inherent in the estimation of the sound power level of any noise source, coupled with the variability of assumptions regarding the modeling of typical noise sources combine to yield an A-weighted sound level predicted uncertainty on the order of 3 dB(A). This will be related to the expected uncertainty of an Engineering Grade sound survey suggested in international standards, such as ISO 6190. However, since ISO 6190 uncertainty is intended to be the measurement uncertainty, the question arises as to how we are to evaluate such combinations of measurement and predictive uncertainties. The author will discuss and defend the view that such uncertainties are additive and will propose the method of combining these effects. The modeling variables to be considered will be confined to the nature of the distributions of the source sound power level over the surface of the actual sound source, and the effects such assumptions have when considered in conjunction with barriers.