Abstract
A new method for evaluating the acoustical properties of porous materials is described here. To implement the procedure, a two-microphone standing wave tube was modified to include: a new sample holder; a section that accommodated a second pair of microphones downstream of the sample holder; and an approximately anechoic termination. A four-point sound pressure method was then used to estimate the two-by-two transfer matrix of the material. The transfer matrix can then be used to determine the wave number and characteristic impedance of the material. The procedure has been used to estimate the acoustical properties of two glass fiber materials.
Keywords
Four microphone, Standing wave tube, Transfer matrix, Transmission loss
Subject
Acoustics and Noise Control
Date of this Version
5-1999
Embargo Period
3-4-2017
Comments
B.H. Song and J.S. Bolton, “Transfer matrix approach to the estimation of the fundamental acoustical properties of noise control materials,” Proceedings of the 1999 SAE Noise and Vibration Conference, SAE Publication P-342 (1999-01-1667), ISBN 0-7680-0410-1, pp. 125-137, Traverse City, Michigan, May 1999.