Patent ID: 6901147

Claim:
A three-dimension active silencer, comprising: a measuring unit configured to detect a signal relating to a sound radiated from a target sound source which is located in a closed box, a plurality of additional sound sources arranged around the target sound source, a microphone arranged at a predetermined position for detecting a sound power at the position, and a controller configured to control respective amplitudes of the additional sound sources which can be different from an amplitude of the target sound source and respective phases of the additional sound sources, based on the signal detected by the measuring unit, in such a manner that the microphone detects the lowest sound power, wherein the additional sound sources are arranged in such a manner that a position x p of the target sound source, respective relative positions d i (i=1, 2, . . . , N) of the N additional sound sources from the target sound source and a wave number k of the sound radiated from the target sound source substantially satisfy a relationship: 1 N ⁢ ⁢ ∑ i = 1 N ⁢ ⁢ cos ⁢ ⁢ k ⁢ ⁢ ( x p - d i ) - cos ⁢ ⁢ k · x p ≅ 0.