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 was proposed by G. B. B. Chaplin at the beginning of 1980's and applied to reduce purr of engines and tones of fans, very successfully. This method is useful only for periodic noise, but has a feature that the system identification of the error path is not necessary. This means that the transfer function of the error path is automatically estimated in this algorithm. Therefore, this method is supposed to be very useful in the case that an error point is moving. The single channel WS method has been developed and applied to engine noises and fan tones as mentioned above. 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 paper, a newly developed multi-channel WS ANC algorithm is proposed, and some experimental results using dual channel WS system are reported.
