Active control of vehicle?s interior sound field with considering acoustic structural coupling

The sound level inside the automobile cabin plays a major role on passengers’ comfort. The sound field inside the vehicle cabin depends on acoustical and structural characteristics and also interaction of acoustical and structural domains. In this paper, a coupled acoustic structural modal and harmonic analysis of simple automobile is performed with the methods of direct coupling (with finite element tool) and modal coupling. So with comparison of results from these two methods, the accuracy of modal coupling method is investigated. Also the optimal MIMO controller is designed to reduce sound level at occupants’ ear positions. The results of coupled and uncoupled modal analysis show that the contribution of uncoupled acoustical and structural modes on coupled response could be estimated and used to understand booming phenomena. Also the presented state space model, which is constructed based on uncoupled modes, shows a good accuracy and reduces computational costs significantly. The results of time and frequency response of sound pressure level at occupants’ ear positions show that the designed controller is attained to attenuate sound field at desired frequency range and the area of quiet zone inside the cabin consists of all occupants’ hearing positions and therefore controller acts globally successful in desired frequency range.