Technical noteInfluence of the search radius in a noise prediction software on population exposure and human health impact assessments

Engineering software products allow for quantifying environmental noise and a population's exposure to road traffic noise which can then be linked to human health damage. This paper investigates the impact of the search radius, a parameter used in emission and propagation models, on noise exposure results. The search radius is the threshold distance from which noise sources are not considered anymore in the exposure assessment. To understand the influence of this parameter on the evaluation of population's exposure, the search radius has been successively fixed to three different values (500 m, 1000 m and 2000 m) in four different geographical situations (village, industrial, suburban and inner city). The result of this investigation highlights several points. First, despite a search radius often fixed to 1000 m by noise prediction software users, going up to 2000 m shows significant increase in population's exposure. Second, the impact of a change in search radius is very dependent of the presence of preponderant noise sources. Third, increasing the search radius can quickly lead to an impractical calculation time. A solution to avoid underestimating the exposure without increasing too much the calculation time may be to only account for preponderant noise sources beyond a given distance.