A transfer-matrix approach for estimating the characteristic impedance and wave numbers of limp and rigid porous materials

• DOI: 10.1121/1.428404
• Publication Date: 2002-07-26T14:08:13Z
• Authors: Bryan H. Song; J. Stuart Bolton
• Keywords: Transfer matrix; Anechoic chamber; Structural acoustics; Matrix (chemical analysis); Transfer-matrix method (optics)

A method for evaluating the acoustical properties of homogeneous and isotropic porous materials that may be modeled as fluids having complex is described here. To implement procedure, a conventional, two-microphone standing wave tube was modified to include: new sample holder; section downstream holder accommodated second pair microphone holders an approximately anechoic termination. Sound-pressure measurements at two upstream locations were then used estimate two-by-two transfer matrix material samples. The experimental has been most widely in past measure silencer system components. That procedure made more efficient here by taking advantage reciprocal nature sound transmission through layers. isotropic, rigid or limp layer can easily identify material's characteristic impedance number, from which other quantities interest calculated. glass fiber material: good agreement found between estimated those predicted using formulas Delany Bazley.