Three-dimension active silencer

Abstract

A three-dimension active silencer includes a measuring unit for detecting 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 are arranged around the target sound source. A microphone is arranged at a predetermined position for detecting a sound power at the position. A controller is adapted 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. 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 can substantially satisfy the following expression. 1 N ⁢ ∑ i = 1 N ⁢   ⁢ cos ⁢   ⁢ k ⁡ ( x p - d i ) - cos ⁢   ⁢ k · x p ≅ 0 According to the feature, it can be achieved to reduce the total sound power in the closed box including the target sound source.

1 - 7 . (canceled)  
   
   
       8 . A three-dimension active silencer for both a first target sound source and a second target sound source, comprising: 
 a first additional sound source arranged around the first target sound source,    a second additional sound source arranged around the second target sound source,    a first microphone arranged at a first predetermined position for detecting a sound power at the first position,    a second microphone arranged at a second predetermined position close to the second target sound source for detecting a sound power at the second position,    a second controller configured to control respective amplitudes of the second additional sound sources and respective phases of the second additional sound sources, in such a manner that the second microphone detects the lowest sound power, and    a first controller configured to control respective amplitudes of the first additional sound sources and respective phases of the first additional sound sources, in such a manner that the first microphone detects the lowest sound power,    wherein:    a plurality of second additional sound sources are arranged around the second target sound source, and    a volume velocity of the second target sound source is substantially equal to a sum of respective volume velocities of the plurality of second additional sound sources.    
   
   
       9 . A three-dimension active silencer for both a first target sound source and a second target sound source, comprising: 
 a first additional sound source arranged around the first target sound source,    a second additional sound source arranged around the second target sound source,    a first microphone arranged at a first predetermined position for detecting a sound power at the first position,    a second microphone arranged at a second predetermined position close to the second target sound source for detecting a sound power at the second position,    a second controller configured to control respective amplitudes of the second additional sound sources and respective phases of the second additional sound sources, in such a manner that the second microphone detects the lowest sound power, and    a first controller configured to control respective amplitudes of the first additional sound sources and respective phases of the first additional sound sources, in such a manner that the first microphone detects the lowest sound power,    wherein:    a distance between the second position where the second microphone arranged and the second target sound source is substantially equal to a distance between the second position and the second additional sound source,    a plurality of second additional sound sources are arranged around the second target sound source, and    a volume velocity of the second target sound source is substantially equal to a sum of respective volume velocities of the plurality of second additional sound sources.    
   
   
       10 . A three-dimension active silencer for both a first target sound source and a second target sound source, comprising: 
 a first additional sound source arranged around the first target sound source,    a second additional sound source arranged around the second target sound source,    a first microphone arranged at a first predetermined position for detecting a sound power at the first position,    a second microphone arranged at a second predetermined position close to the second target sound source for detecting a sound power at the second position,    a second controller configured to control respective amplitudes of the second additional sound sources and respective phases of the second additional sound sources, in such a manner that the second microphone detects the lowest sound power, and    a first controller configured to control respective amplitudes of the first additional sound sources and respective phases of the first additional sound sources, in such a manner that the first microphone detects the lowest sound power,    wherein:    the second position where the second microphone is arranged is substantially intermediate between the second target sound source and the second additional sound source,    a plurality of second additional sound sources are arranged around the second target sound source, and    a volume velocity of the second target sound source is substantially equal to a sum of respective volume velocities of the plurality of second additional sound sources.    
   
   
       11 . A three-dimension active silencer for both a first target sound source and a second target sound source, comprising: 
 a first additional sound source arranged around the first target sound source,    a second additional sound source arranged around the second target sound source,    a first microphone arranged at a first predetermined position for detecting a sound power at the first position,    a second microphone arranged at a second predetermined position close to the second target sound source for detecting a sound power at the second position,    a second controller configured to control respective amplitudes of the second additional sound sources and respective phases of the second additional sound sources, in such a manner that the second microphone detects the lowest sound power, and    a first controller configured to control respective amplitudes of the first additional sound sources and respective phases of the first additional sound sources, in such a manner that the first microphone detects the lowest sound power,    wherein:    a sound radiated from the second target sound source has a substantially same frequency, a delayed amplitude and a delayed phase, with respect to a sound radiated from the first target sound source.    
   
   
       12 . A three-dimension active silencer for both a first target sound source and a second target sound source, comprising: 
 a first additional sound source arranged around the first target sound source,    a second additional sound source arranged around the second target sound source,    a first microphone arranged at a first predetermined position for detecting a sound power at the first position,    a second microphone arranged at a second predetermined position close to the second target sound source for detecting a sound power at the second position,    a second controller configured to control respective amplitudes of the second additional sound sources and respective phases of the second additional sound sources, in such a manner that the second microphone detects the lowest sound power, and    a first controller configured to control respective amplitudes of the first additional sound sources and respective phases of the first additional sound sources, in such a manner that the first microphone detects the lowest sound power,    wherein:    a distance between the second position where the second microphone arranged and the second target sound source is substantially equal to a distance between the second position and the second additional sound source,    a sound radiated from the second target sound source has a substantially same frequency, a delayed amplitude and a delayed phase, with respect to a sound radiated from the first target sound source.    
   
   
       13 . A three-dimension active silencer for both a first target sound source and a second target sound source, comprising: 
 a first additional sound source arranged around the first target sound source,    a second additional sound source arranged around the second target sound source,    a first microphone arranged at a first predetermined position for detecting a sound power at the first position,    a second microphone arranged at a second predetermined position close to the second target sound source for detecting a sound power at the second position,    a second controller configured to control respective amplitudes of the second additional sound sources and respective phases of the second additional sound sources, in such a manner that the second microphone detects the lowest sound power, and    a first controller configured to control respective amplitudes of the first additional sound sources and respective phases of the first additional sound sources, in such a manner that the first microphone detects the lowest sound power,    wherein:    the second position where the second microphone is arranged is substantially intermediate between the second target sound source and the second additional sound source, a sound radiated from the second target sound source has a substantially same frequency, a delayed amplitude and a delayed phase, with respect to a sound radiated from the first target sound source.