Sound insulation design using membrane and locally resonant structure

Abstract

In this study, we propose a design for sound insulation that utilizes a membrane and a locally resonant structure in tandem. A membrane serves as an excellent sound insulation structure in itself, but it can also be used to improve sound insulation performance by changing the dynamic characteristics of the sound insulation panel. In the case of the latter, there is an advantage of improving sound insulation performance in several bands without a large increase in weight. However, because the resonance band occurs at a relatively lower frequency than the anti-resonance band, it is difficult to block noise at frequencies below the anti-resonance band. To address this, we added a locally resonant structure that operates within the associated band. Because the anti-resonance caused by the locally resonant structure occurs at a lower frequency than the resonance, it can compensate for the deterioration band caused by the membrane-cavity. These effects have been verified through a sound transmission loss simulation of the unit structure at the normal and oblique incidence condition. Furthermore, the soundproofing bands of the product (plate and enclosure) were validated through SPL experiments.