Expected Mean in an Environmental Noise Measurement and its Related Uncertainty

In the context of the implementation of the Environmental Noise Directive 2002/49/EC a study on noise measurement uncertainty was performed. Averaging over different samples of noise measurements , there might be assumptions over the distribution and independency of the samples. In the context of environmental noise, this might be the case of a series of measurements of a constant noise source like an industrial plant or a fluctuating noise source like road traffic. Using a series of 15 minutes LAeq samples, the average of these values is usually considered as the expected mean, however, the error caused by the specific selection of the samples is not usually evaluated. Statistically speaking, before establishing an average value, at least the distribution of the samples and the effect of adding-up several uncertainties should be evaluated. This article focuses on the mathematical formulas which could be used and discusses the differences in assessing the expected mean for normally distributed values, or for log-normally distributed, and finally suggests an approach to properly adding-up all uncertainties related to a long-term environmental noise measurement campaign.JRC.I.2-Chemical assessment and testin