Study of sound absorption by using acoustic impedance tube

Abstract

Acoustic absorption is the process of reducing sound energy by passing sound waves through a medium or striking a surface. The absorptivity is the property of a material that converts the acoustic energy of sound waves into another form of energy, usually heat, so as to control noise within a boundary. The absorptivity of a given material depends on frequency and is affected by size, shape, location, and the mounting method used.

The experiments carried out in this project were aimed mainly to explore a number of parameters which affect sound absorption. These parameters include the perforation distribution on the perforated plate and the different material combinations of multi-perforated plates. The effects of porous materials were also investigated in this project.

Specimens were fabricated for the experiments, and a two-microphone impedance tube was used to study how the sound absorption coefficient of a micro-perforated plate is affected by the above mentioned parameters. The results are then analysed and presented in this report.