Research On Adaptive Active Noise Control Technology Of Helmet

With the increasing of the aircraft engine power and the number of auxiliary, the noise in the cockpit of military is also increasing. The noise is always concentrated in the low frequency band, and the machine voice, therefore it is very necessary to control the aircraft noise based low-frequency. Active noise controlling has become a hot point in the field of noise control in recent decades. Active noise control helmets are included analog and digital, which is a more successful example on the active noise control technology applications in engineering. Adaptive active noise control aviator’s helmet is a digtal active noise helmet which is installed to a adaptive active noise control devices based on the traditional avistor’s helment. It uses the technology to reduce the low frequency aircraft noise and thus enhance the integrated noise reduction. The applications of adaptive active noise control in reducing the aircraft noise will be mainly researched in this paper.First, this paper describes the development of active noise reduction earmuffs history and current status, study the theory of adaptive noise reduction system, including the theory of adaptive filter and algorithms, adaptive feed forward control systems and off-line modeling. Application of computer adaptive active noise cancellation system is simulated, by comparing the noise reduction effect and analysis of the filter order, convergence factor, the noise signal band and the modeling accuracy of the impact of adaptive active noise reduction algorithm, and obtained off-line modeling accuracy through modeling process for off-line simulation.Second, the platform is based on the development board of VC5509A on the text. The algorithm of FXLMS and the off-line modeling are proved by experiment. Through analying of the text data, the system that was built has a certain capability of noise reduction.