In the present study, we consider a cylindrical structure with thin plate at both ends and investigate vibroacousitc coupling between the plate vibrations and internal sound field when an external harmonic force is applied to one end plate, regarding such a coupling phenomena as one of the available measures to amplify acoustic energy. This coupling is theoretically and experimentally investigated by considering the behavior of both plates and the acoustic characteristics of the internal sound field for varying and the cylinder length. In the analytical model, the end plates are supported circumferentially by springs in order to obtain support conditions that are as close as possible to the actual condition in the experiment due to adjustments of spring stiffnesses. The coupling phenomena are estimated theoretically from the relationships between characteristics of the plate vibrations and the sound field with respect to some vibration modes. These theoretically results are verified experimentally through an excitation experiment using an experimental apparatus that is emulated by the analytical model. Moreover, the experiment of electricity generation demonstrates that the coupling phenomena are the available measure to amplify energy of the systems and to extract that, performed with piezoelectric elements.