抄録
It is difficult to reduce the noise of a moving evaluation point with Active Noise Control (ANC) technique. This is because that ANC technique can control only narrow area. Therefore to expand quiet area is necessary. Although we showed that it is possible to expand quiet area against pure tone in the previous study, but it is not yet capable against random noise. In this paper, we propose the new method for expanding quiet area against random noise. Two conditions, noise reduction and noise passage conditions, for an error microphone are investigated. Under the noise reduction condition, noise is reduced at the position of error microphone. On the other hand, under noise passage condition, all control sound are cancelled each other at the position of error microphone. These conditions depend on a standard frequency. When the standard frequency is same to the noise frequency of pure tone, it makes noisier area narrow to set error microphones meeting these conditions. Accordingly, we think that to meet these conditions at many standard frequencies make noisier area narrow in random noise effectively. The control effect is shown by the numerical simulations.
