Abstract:
Analytic expressions for the transmission and reflection coefficients of higher-order modes in acoustic waveguides are developed and explored.When written in matrix form the equations take on the standard form of an impedance discontinutity. Numerical results for a right angle bend and a T junction show that there is significant coupling between modes, especially to the plane-wave mode. The results indicate that modal coupling cannot be ignored in the design of active and passive attenuators that need to work at higher frequencies.