Assessment of the sound reduction index provided by noise barriers with low sound insulation

Abstract

In the realm of environmental noise control, the emergence of metamaterial-based acoustic barriers, such as sonic crystal noise barriers (SCNBs), represents a significant innovation due to their unique ability to manipulate sound waves. Despite their growing popularity, accurately assessing their efficacy remains a challenge. In one of the current standard methods, as outlined in EN 1793-2:2012, overestimates the sound insulation in cases with low sound insulation. This becomes problematic for sonic crystal noise barriers, which show low sound insulation at certain frequencies. Consequently, this standard method overestimates the sound reduction index in such cases. In this paper, an alternative formulation for the determination of the sound reduction index is proposed to avoid the sound insulation overestimation when dealing with sonic crystal noise barriers. The proposed formulation is validated by both numerical simulations and experimental measurements.