Active noise control for a moving evaluation point using stepsize vector

In three-dimension acoustic field, it is difficult to control in the whole room using active noise control (ANC) technique. Instead, around-head-control is investigated in this paper. By using around-head-control method, an object person can get the noise reduction effect without controlling in the whole space, because it makes around the head quiet locally. Therefore, to realize around-head-control, it is necessary for a controller to follow the head movement. However, there is a problem that the control effect under the movement is worse, and the recovery of control effect after movement is slow by conventional ANC. Against this problem, we propose the new method of improving the adaptation speed when an evaluation point moves. In the algorithm, the updating size appropriate to each coefficient of the adaptive filter is calculated by using a step size vector. The step size vector is calculated from the coefficient of adaptive filter before updating. The validity of the proposal method is shown by the numerical simulation and the experiment in an anechoic chamber.