Using the Schroeder diffuser to improve parallel noise barriers' performance

In recent years, noise barriers are considered as one of the main ways to control traffic noise pollution. In this study, two different types of noise barriers: the parallel barrier model with primitive root diffuser (PP) and the parallel barrier model with quadratic residue diffuser (PQ) were designed, and the two-dimensional boundary element method was used to predict their efficacy in noise control. The results of this research compared the improvement in performance of parallel barriers covered with the primitive root diffuser (PRD) with parallel barriers covered with the quadratic residue diffuser (QRD) and the simple parallel barriers (P). Efficacy in different frequencies, using the diffuser with different depths based on the PP model was studied and was compared to the PQ barrier and a reference barrier (P) without any wells. The results showed that the efficacy of the parallel sound barrier arm covered by PRD in different intended receiver positions was higher than QRD and the simple parallel sound barrier arm.