Active Noise Control Assuming Quiet Zone Move

Active noise control (ANC) in 3-dimensional sound field, e.g. an office room, is investigated in this paper. Since the size of the controlled area normally depends on the wave length of the target noise, it is difficult to control in the whole room using ANC technique. Instead, around-head-control is investigated in this paper. To realize the around-head-control, an evaluation point is required to correspond with the head movement while controlling. However, the evaluation point movement while controlling has not been considered in a conventional ANC. Against this problem, the new algorithm is proposed in this paper. The algorithm calculates filters as function of position by using a Time-Delay filter and a Distance-Attenuation coefficient. The Time-Delay filter and the Distance-Attenuation coefficient are calculated from the position of the evaluation point. Computer simulations with acoustic characteristics in an anechoic chamber and an ordinary room are carried out. The validity of the proposed algorithm is shown from these simulations.