Acoustic performance of noise barrier based on sonic crystals with resonant elements

Abstract

Recent years have seen a growing interest in the potential for the use of sonic crystals as noise barriers. The frequencies of highest attenuation can be found by assuming that an integer number of half wavelengths fits the distance between the scatterers. However, this leads to a reduction in its usefulness as a viable noise barrier technology, due to the necessary increase in overall crystal size to increase frequency range of noise reduction. Additional attenuation bands may be achieved if the array is composed of resonant elements instead of solid cylinders. The paper presents resonant sonic crystal barrier that could be applied to stationary but movable noise sources eg. power generator. The results of simulation results were confronted with the results of previous work in this field. This work presents also sound insulation measurements conducted over sonic crystal noise barrier according to the European standard EN 1793-6. In most of the reference literature, sound insulation and reflection properties of sonic crystals are measured or a diffuse sound field or in a direct sound field including the top and side edge diffraction effects together with the transmitted (or reflected) components. The aim of this work is to perform free-field measurements over a real-sized sample in order to verify the points of strength and weakness of the application of standardised measurements to sonic crystals.