Study of sound absorption by using acoustic impedance tube

• Main Author: Ho, Tan Thuy
• Other Authors: Huang Xiaoyang
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68082
• Institution: Nanyang Technological University

In acoustics, sound absorption is one of the major definitions and an important factor to be considered when designing an occupational place. Acoustic engineers need to fully understand the absorption property of building materials to select the suitable products for solving various acoustical problems. The sound absorption coefficient is the standard rating of this property. It can be measured by using the reverberation room method for random incidence sound or the impedance tube method for normal incidence sound. Porous, fiber-based materials are the mostly used solutions by acousticians due to their cost efficiency and proven effectiveness. However, these materials still have certain disadvantages and most importantly, pose as a health hazard for human. Hence, the focus of this project is on studying the sound absorption of non-porous, non-fibrous material with a Brüel & Kjær Two-Microphone Impedance Tube Type 4206. The samples of interest are of resonant type absorbers, namely 3D-printed membrane absorbers, micro-perforated panel absorbers backed with corrugated paper, and backed with quadratic residue diffuser (QRD). In the end, the effects of membrane thickness, the effects of different combinations of corrugated flute thickness and air cavity as well as the effects of additional QRD backing on sound absorption coefficient are obtained and reported.