Noise prediction considering differences of sound characteristics of noise barrier

In noise prediction for railway viaducts using numerical analysis, walls such as noise barriers made of adequately thick concrete are often treated as rigid walls. A sound-insulating panel such as a polycarbonate sheet of 8mm thick is sometimes used as additional noise barriers, but its sound insulation performance is generally lower than that of concrete noise barrier. Therefore, it is desirable to consider the realistic sound insulation performance to enhance the accuracy of noise prediction. In this study, the sound insulation performance of the panel is regarded as a damping component and its characteristics is given by associating the complex sound speed with the transmission loss of the panel. The variation of noise levels outside a railway viaduct in increasing the height of the noise barrier is calculated by a finite element method and indicate good agreement with the past findings.