On the accuracy of modal analysis in reverberant acoustical systems with damping

That the modal analysis method works well regardless of the amount of damping in the system, provided that modal coupling is included in the analysis, is shown. The soundfield produced by a vibrating piston in a tube with an absorptive end is calculated. An exact solution is compared to results computed by modal analysis with and without the inclusion of modal coupling. Recent published results, which did not include the effects of modal coupling, incorrectly concluded that discrepancies were due to limitations of modal analysis, rather than the uncoupling assumption.