Acoustical Efficiency of a Sonic Crystal Assisted Noise Barrier

This research work aims at evaluating the acoustic performance of a noise reducing device which combines sonic crystals with a conventional noise barrier. Numerical simulations, using a 2D Boundary Element Method (BEM), are carried out to evaluate their acoustic properties in terms of insertion and reflection losses due to the addition of the sonic crystal elements. The studied so-called sonic crystal assisted noise bather is 3 m high and 1 m wide and is composed of two periodic bands of scatterers combined with a rigid straight bather. Resonant cavities are used to produce extra insertion loss at some frequencies of resonance below the band gaps. Improved attenuation properties are found when resonant scatterers (cavities) and absorbent materials are combined. Our results show a significant extra insertion loss due to the addition of the sonic crystal elements for middle and high frequencies of typical road traffic noise. On the other hand, the extra reflection loss is limited.