ESTIMATION OF NOISE SHIELDING BY BARRIERS.

ESDU 79011 gives a method for predicting the total attenuation due to a sharp-edged barrier between the source and the observer. The major source of attenuation is that due to diffraction at the edges, and a method is given for obtaining that for an infinite barrier. There are additional components of attenuation which must also be taken into account due to the increased propagation path between the source and the observer, and possibly due to any directivity of the noise source. Those components are also treated, using ESDU 78002 to predict the increased atmospheric attenuation. The theoretical basis of the diffraction prediction is included, the application of the estimation method to a finite barrier by summing the diffractions at each edge is explained, and a program listing in both BASIC and FORTRAN is given for which appropriate media (magnetic tape or punched cards) are available as ESDUpac 1009. A comprehensive practical worked example illustrates the use of the method.