Influence of traffic noise emission spectra on the design of barriers

Acoustical barriers are widely used and the methods to estimate the noise attenuation they produce are well established. Although data for noise spectra for different conditions of road traffic are available, the interim method recommended in the European Union considers only one kind of spectrum. This has important implications in the dimensions of the barriers used for noise attenuation, generally leading to over sizing with the corresponding economical costs. The intent of this paper is to show the practical importance of the spectra used when determining dimensions of acoustical barriers and the level of uncertainty that may occur when only one kind of spectrum is considered.