Using Maekawa's chart to calculate finite length barrier insertion loss

Abstract This paper describes a simple model for the calculation of finite length barrier insertion loss. The model is based on the concept of minimum diffracted paths. It makes use of Maekawa's empirical curve to estimate the attenuation associated with each diffracted path. However, instead of summing the energy contributions of the diffracted waves as suggested by Maekawa (Applied Acoustics, 1 (1968) 157-73), a new formulation of the phase relationships between the waves is developed to allow pressure summation. The result is a model which is simple to use and yet has accuracy substantially better than Maekawa's energy summation method, in predicting both narrow and octave band insertion loss of finite length barriers. Extensive model experiments are used to verify the model. It is believed that the model is both simple and accurate enough to replace Maekawa's energy summation method in engineering practice.