Normal Incidence of Sound Transmission Loss of a Double-Leaf Partition Inserted with a Microperforated Panel

A Putra,M S Py,A Y Ismail,Md R Ayob,R Ramlan

doi:10.1155/2013/216493

A Putra, M S Py + Show 3 more

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https://doi.org/10.1155/2013/216493

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Abstract

A double-leaf partition in engineering structures has been widely applied for its advantages, that is, in terms of its mechanical strength as well as its lightweight property. In noise control, the double-leaf also serves as an effective noise barrier. Unfortunately at low frequency, the sound transmission loss reduces significantly due to the coupling between the panels and the air between them. This paper studies the effect of a microperforated panel (MPP) inserted inside a double-leaf partition on the sound transmission loss performance of the system. The MPP insertion is proposed to provide a hygienic double-leaf noise insulator replacing the classical abrasive porous materials between the panels. It is found that the transmission loss improves at the troublesome mass-air-mass resonant frequency if the MPP is located closer to the solid panel. The mathematical model is derived for normal incidence of acoustic loading.

Highlights

A double-leaf structure is a common structural design for many engineering applications
It can be seen that inserting another solid panel between the double panels (TL) yields the second resonance at 280 Hz corresponding to the gap between the middle and the back panel
The sound transmission loss of a double-leaf partition system inserted with microperforated panel (MPP) under normal incidence of acoustic loading has been reported

Summary

Introduction

A double-leaf structure is a common structural design for many engineering applications. There remains a problem on the double-panel which is the weak sound transmission loss (STL) performance at low frequency due to the “mass-air-mass” resonance. This causes the double leaf to lose its superiority over the single-leaf [1]. Several works have been established to solve this problem This includes employing absorptive materials inside the gap of a double-leaf, for example, fiberglass [2] and rockwool [3] which can effectively increase the STL due to additional damping to the air layer provided by the absorbent. The section describes the derivation of the mathematical model and presents the simulation results of the effect of the MPP insertion, in terms of its location in the gap as well as its hole size and perforation ratio, on the sound transmission loss. Numerical modelling technique is required, but this is beyond the scope of this paper

Governing Equations

Analytical Results

Experiment

Conclusions