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In a vibro-acoustic cavity system, vibrations of the flexible surfaces of the cavity affect the acoustic field inside the cavity and the acoustic field inside the cavity affects the vibrations of the flexible surface. In practice, acoustic field can be generated either due to disturbances acting on the structure of the cavity or due to acoustic disturbances entering into the cavity. In these situations, global control of acoustic pressure has been achieved by minimizing acoustic potential energy in the cavity. Studies further show that global control at cavity controlled resonances can be more effectively done using the acoustic control actuators, while at panel controlled resonances, use of structural control actuators is more effective. Previous studies have considered global active noise control in cavities when both structural and acoustic control actuators are employed. However, these studies either considered only acoustic disturbance or structural disturbance to be present. In practice, many a times, both structural and acoustic disturbances are responsible for interior noise. In view of this, the present work considers global active control of interior noise using both structural and acoustic types of actuators under the presence of both structural and acoustic disturbances. Global acoustic potential energy is minimized and the expressions for the optimum values of inputs to structural and acoustic actuators are developed for feedforward control. A numerical study of a 3D rectangular box cavity with a flexible plate is presented to test the optimal solutions for feedforward control. Acoustic and structural modal responses before and after optimal control are analysed to understand the behavior of the acoustic and structural actuators. It is found that at cavity controlled resonances, acoustic control source alone can provide significant minimization in acoustic potential energy without increasing kinetic energy of the panel but at panel controlled resonances, both acoustic and structural control sources are required to have a significant minimization.
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