Noise control by barriers—Part 1: Noise reduction by a thick barrier

This paper presents a method of estimating the excess attenuation of noise by a thick barrier. In this method, the excess attenuation of noise by a thick barrier is assumed to be composed of two parts, one being the effect of a virtual thin barrier with the same height and the other the effect of thickness. A single chart for estimating this thickness effect is offered under conditions which only permit an error of a few decibels. The validity of the method presented here is verified by comparing the estimated with the measured values. Consequently, this method may be useful for the purpose of estimating the excess attenuation of a band of noise by the barrier whose thickness is larger than half a wavelength.