ON PERFORMANCE OF SONIC CRYSTALS IN PRESENCE OF GROUND PLANE

摘要

The performance of a sonic crystal is characterized by the so-called Bragg band gaps where its insertion loss is very high. This effect makes sonic crystals effective noise barriers in the particular frequency intervals. However the presence of boundaries in the acoustic environment can have a great impact on the sonic crystal spectral properties. In this paper the acoustic environment is a half-space bounded by a rigid/impedance boundary that effectively models the presence of a ground plane. Using multiple scattering method the barrier insertion loss is calculated for various types of barrier scatterers (rigid cylinders and thin elastic shells). Using boundary element method the barrier insertion loss is calculated for various types of a locally reacting ground plane. The type of the cylindrical scatterers and the impedance of the ground are shown to have a considerable effect on the performance of the sonic crystal.