Barriers are commonly used to reduce traffice noise. The construction cost and its performance are two major factors for consideration in the design stage. Sealing horizontal gaps between the noise barrier and the ground is normally required to ensure an 'air-tight' condition. This has a significant cost implication because a possible elimination of this procedure will save time and construction cost. On the other hands, vertical gaps are inevitable in some cases as they are required, for example, in the installation of a lamppost between two sections of a barrier. However, any noise leakage due to the vertical and horizontal gaps will lead to the degradation of the acoustic performance of the barrier. The purpose of this work is to investigate the effect of gaps in barriers. In the present study, a numerical model is developed to predict noise levels behind thin barriers of various gap sizes. As opposed to many computationally intensive schemes based on the Boundary Integral Method, the proposed numerical methodology enables one not only to study a two-dimensional model but also to investigate the sound fields behind a finite length barrier. In addition, indoor experiments have been conducted to validate the theoretical predictions.
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