624 多チャンネル波形同期法を用いたANCの基礎研究

Abstract

It is strongly required to reduce noise at moving person's ears in a noisy room by some active noise control (ANC) techniques. In the case of using fixed secondary sources, some multi-channel control methods are necessary. Various methods have been proposed for this on-line system identification, but it takes time to identify the error paths and the system can't follow quick movement of the error microphones, in the case of multi-channel system. On the other hand, Wave Synthesis (WS) Method is only useful for periodic noises, for example, purr of engines and tones of fans. But the feature of this algorithm is not to need the system identification of the error path. When error point moves, this algorithm can follow it. The single channel WS method has been developed and applied to purr of engines so far and has obtained great noise reduction. However, a multi-channel system using WS algorithm has not been established. According to these backgrounds, the final target of this research is to develop multi-channel WS ANC system and apply it to reduce noise at person's ears who move in a noisy room with periodic sound. In this report, at, first, we deduced multi-channel Wave Synthesis Algorithm. Next, we performed the experiment in the single channel system and checked convergence time. Consequently, it's confirmed that high order harmonics components decrease quickly. In addition we checked how quick to follow movement of the error microphone.