A method is provided for the prediction of the total attenuation of sound due to a sharp-edged barrier positioned between the source and the observer. The major attenuation is that due to diffraction at the barrier edges. Additional components of sound attenuation@ which are accounted for@ are those due to the increased propagation path length between source and observer@ and to source directivity. Guidance is also given on possible sound reduction resulting from atmospheric attenuation. The theoretical basis of the prediction procedure is also described. Its application to the estimation of sound attenuation by a finite barrier by considering the diffraction at each edge is explained. Guidance is given on the maximum of noise shielding by a barrier. The prediction procedure is provided in both graphical form and as a computer program known as ESDUpac A7911. An additional program B7911@ which can be used to create required input files@ is also provided.