Variability in road traffic noise levels

Environmental noise levels can vary over a wide range as a result of the diversity of site conditions and activities occurring during field measurements. This variability, extremely important for a correct measurement interpretation, is often a source of disagreement when applying standards and regulations, as there is no consensus about how to estimate and present it. The paper contributes to this technical debate by investigating the statistical variability associated with a large measurement database acquired under field conditions. The database consists of 2 week’s noise recordings at each of 50 separate locations in residential areas affected mainly by road traffic noise. The results show increased variability (standard deviations) at the lower values of either logarithmic or arithmetic mean L_Aeq over the time periods investigated. It is anticipated that the observed relationships may be of assistance when estimating the noise level variability and the uncertainty associated with a noise measurement affected by road traffic or other environmental noise sources.