Acoustical Analysis and Optimization for Micro-Perforated Panel Sound Absorber

Abstract

The main objective of this study is to maximize the rate of sound absorption by applying the parameters of micro-perforated plate (MPP) such as the holes diameter, holes spacing, thickness of MPP, and air cavity depth of MPP. In this study, an optimization algorithm – Firefly algorithm is adopted to determine an optimum set of four parameters for MPP. There are four pieces of MPP with different holes of diameter and spacing was used as specimens. The two-microphone impedance tube method was used to measure sound absorption coefficient (SAC) of MPP sound absorber according to ASTM E1050-12 standard. From the experiments, MPP C (hole diameter = 0.5 mm, hole spacing = 7 mm) for both air cavity depth (30 & 60 mm) score the highest SAC which is 1.00 while MPP B (hole diameter = 0.9 mm, hole spacing = 5 mm) obtain the lowest SAC for air cavity of 30 and 60 mm, which are 0.62 and 0.54 respectively. Then, the firefly algorithm is applied to obtain the optimal solution the set of parameters for MPP sound absorber to reduce the noise level. Hence, it is concluded that by increasing the air cavity depth, holes spacing, and decreasing holes diameter size can increase the rate of sound absorption for MPP. The optimal set of parameters obtained from this study for MPP sound absorber for air cavity, hole diameter and holes spacing are 30, 0.71 mm and 0.5 respectively.KeywordsMicro-Perforated Plate (MPP)Impedance tubeSound Absorption Coefficient (SAC)