Effect of Sidewalls on Sound Transmission Loss Through Sonic Crystal

Abstract

Sonic crystals are the periodic arrangements of scatterers embedded in a homogeneous material. Their ability to prevent sound wave to propagate in a particular range of frequency demonstrates their use as potential noise barriers. The sonic crystal considered in this work is an array of PVC cylinders (5 × 5) in air bounded by acrylic sheets. This paper studies the sound transmission loss in the sonic crystal by changing the location of the sidewalls. The optimized location of sidewalls of the sonic crystal to get wide band gap and high sound transmission loss has been investigated. To increase the transmission loss, a periodic structure having bi-periodicity, i.e., periodicity in two perpendicular directions is introduced. Both computational (Finite Element simulation) and experimental work has been performed to study the sound transmission loss and the band gaps. To bridge the gap between the two results, an improved finite element model has been proposed with an aim to replicate the experimental situation more closely. Generally, in experiments, insertion loss is calculated while numerically transmission loss is computed, and the two are compared. In this paper, a comparison between insertion loss and transmission loss has also been made numerically, which is compared with the experimental results.