Research Of Active Noise Control In Enclosed Sound Field

Active noise control is a new method which is developed in recent years. It works well at low frequency which is a difficult problem for traditional noise control methods. The research of active noise control in enclosed sound field has great significance.This dissertation which was according as the theory of active noise control analyzed the configurations and the theories of feedforward control system and feedback control system first. The results of an emulator were used to compare the merits and defects of the two kinds of control systems and the conditions of the two kinds of control system in points were given. The second, the FXLMS algorithm which was used in active noise control system was deduced and was compared with LMS algorithm. The reasons of capability of the algorithm was affected were analyzed through the emulator and the factors which influenced astringency, stabilization and noise control capability were given. The third, designed and made a model of enclosed field and built an active noise control system though analyzing and choosing the instruments and digital signal processor. System control software was also compiled. Finally experimentations in five different conditions were conducted with the active noise control system.The results indicated that the active noise control system of enclosed sound field was in effect. It could reduce the sound pressure level of some frequencies in a limited area.