Active noise control for a moving evaluation point using stepsize vector and interpolation of secondary path

In a three-dimensional acoustic field, it is difficult to control sound in the whole room using the active noise control (ANC) technique. Instead, an around-head-control is investigated in this paper. It can reduce noise locally around the head with the simple equipment. To realize the around-head-control, it is necessary for a controller to follow the head movement. However, there is a problem that the control effect during the movement is worse, and the recovery of control effect after the movement is slow by the conventional adaptive algorithms. Against this problem, we propose a new method of improving the adaptation speed while the evaluation point moves. The algorithm can control noise by interpolating the secondary path of the Filtered-x algorithm during the movement. 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 coefficients of the adaptive filter before updating. The validity of the proposal method is shown by the numerical simulation.