| 摘要 |
<P>PROBLEM TO BE SOLVED: To generate a proper secondary sound even in the presence of another noise source in a duct by a device or method which radiates a proper secondary sound for noise propagated in the duct and radiated to reduce the noise by interference. <P>SOLUTION: A noise detection microphone 3 is provided nearby a noise source and a signal processing part 4 generates a control signal according to its detection signal to radiate a secondary sound from a secondary-sound radiation speaker 5. The control signal is optimized to nearly the same amplitude with and the opposite phase from the noise and information on that is obtained by computing the noise propagated from the noise source to a muting point by a duct inside passing noise simulating means 11 and computing the secondary sound through the simulation of a secondary sound simulating means 13. An error signal simulating means 14 adds the computed simulated noise and secondary sound and the control signal is so adjusted as to minimize their error component. Consequently, a decrease in interference by noise generated in the duct 2 can be evaded. <P>COPYRIGHT: (C)2003,JPO |
