| Today, people pay great attention to the interior noise in automobile increasingly, as a result of the improving requirements of ride comfort,conscious of environmental protection and the development of automotive industry. Mostly traditional passive noise control measures in automobile are vibration and sound insulation, noise elimination and sound absorption etc. These methods have good effect on the middle and high frequency noise, but little effect on low frequency noise caused by vibration and sound insulation of automotive body. The active noise control (ANC) technique gains much concern and develops quickly in recent years. Study on reducing low frequency noise inside automotive cabin by the ANC technique is presented in this paper.The control mechanisms of ANC are introduced at first. Then the initial and secondary sound fields are analyzed in an elastic enclosure, afterwards, acoustic simulations of an elastic rectangular enclosure are carried through using the advanced finite element software. The results show that canceling noise by sound have little effect on the noise radiation caused by structural modes; the law of laying secondary source is put it on the anti-nodal plane of several ruling acoustic modes. Simulations about reducing noise excited by engine revolution are done by laying secondary source at proper places on the simplified finite element model of a passenger car. After selecting a filtered-X LMS algorithm, a feedforward adaptive active noise control system is set up to study the characteristic of adaptive algorithm and the effect of the AANC system with the Simulink toolkit. At last, aiming at reducing sound pressure level at some areas inside the car, that is, near the driver's right ear, a lot of experiments are done. Satisfied control results are gained that the AANC system can attenuate noise in some certain region and its stability is good.
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