A numerical procedure for assessing the performance of an active noise and vibration control system for a harmonically excited weakly coupled multimodal vibroacoustic system is presented. The structure and the contiguous acoustic space have been modeled separately with a commercially available finite element analysis package (ANSYS) and then combined using a modal coupling theory for weakly coupled systems. Numerical results are compared against experimental measurements for a finite longitudinally stiffened cylinder with an integral floor. Experimental based response matrices were measured and used to predict the system response. Modal analysis was applied in order to reduce the required effort in determining the response matrix. A design methodology for optimizing the physical control system is reviewed and several trends presented.