Acoustic performance of noise barriers based on sonic crystals

This paper aims at evaluating the acoustic performance of an environmental noise barriers based on sonic crystals. Recent studies showed that that the use of standardized methods intended for classical noise barriers with limited measurement points may not be sufficient to fully evaluate SC barriers. Therefore in this paper direct acoustic vector field mapping was used for sound visualization in close proximity to SC barrier. The sample of SC barrier was made of hollow PVC pipes arranged in a square lattice. A unit cell was defined with six concentric C-shaped resonators based on Elford concept with lattice parameter a = 165 mm. The measurements performed for free-field conditions (EN 1793-6) showed sound insulation index values up to 16 dB in the target frequency range. With the use of 3D scanning measurement of sound intensity visualization of acoustic field were created in order to illustrate behavior of the noise propagation in close proximity to the barrier. The obtained distributions of sound intensity vector in the vertical and horizontal measurement plane indicate the differentiated effectiveness of sound insulation depending on the position and frequency. The results of the research form the basis for developing unified methods for assessing the effectiveness of acoustic insulation of barriers based on sonic crystals.