Ducts with spatially varying properties
Abstract
A duct with a varying crosssection and/or acoustic impedance of its internal surface is represented by a series of small duct sections. Each section has parallel walls and a locally reacting internal surface with constant impedance. The effect of the transition between two ducts of a different crosssection is studied. The ducts are considered bidimensional and the characteristic equation is solved numerically, in this way a set of orthogonal modes are obtained with which the sound field can be synthesized. The amplitudes corresponding to each mode can be obtained from the boundary conditions for pressure and velocity between duct sections. Considering a number N of modes, a system of linear equations with 2N unknowns is obtained (corresponding to the modal amplitudes of the incident and reflected waves). The acoustic behavior of duct transitions is analyzed considering the three fundamental types of impedance (mass character, stiffness character, and damping). (To be presented in Spanish.)
 Publication:

Acoustical Society of America Journal
 Pub Date:
 November 2002
 DOI:
 10.1121/1.4779950
 Bibcode:
 2002ASAJ..112.2427B
 Keywords:

 Acoustic Impedance;
 Acoustics