| 摘要 |
PURPOSE:To eliminate periodic noise by detecting basic frequency of noise component having harmonic wave structure and inputting acoustic signal through a combine filter composed of an attenuation polar by the basic frequency and frequency component having harmonic wave relation with the basic frequency. CONSTITUTION:Microphone 1 are arranged at the receiving point of an acoustic signal in which environmental noise is predominant and input the environmental noise. The basic frequency component of the environmental noise having the harmonic wave structure is detected at a basic frequency detecting part 3 after being converted from the environmental noise to electrical signal. And these data are fed to frequency area combline filtering circuit 5. On the other hand, the microphone 2 inputs even required sound together with the environmental noise and carry out frequency spectral enumeration at frequency spectral enumeration circuit 4 after being converted into the electrical signal and then such enumerated data are fed to the circuit 6. At a frequency area, for input frequency spectrum, the circuit 5 performs the combline filtering through which the basic frequency as well as their high harmonic component in the other word, the frequency component having harmonic wave structure fed to the circuit 5 become null and the noise are eliminated. |
