| 摘要 |
PURPOSE:To reduce influence upon a harmonic structure and simplify a device by providing a howling occurrence band detecting circuit, a control switch, a frequency shifting device, and an adder to reduce the degradation of tone quality. CONSTITUTION:The input signal from a microphone 1 is separated into respective bands through BPFs 2-5, and power is calculated by power calculating circuits 6-9. A howling occurrence band detecting circuit 10 decides the occurrence of howling in a band based on calculation results if power in this band is higher than that of adjacent bands by a prescribed threshold or more, and this band is indicated to a control switch 11. The switch 11 is operated for the indicated band to input a signal to an adder 14. The output of the adder 14 is inputted to an adder 13 through a frequency shifting device 15 and is added to signals in bands other than the band where howling occurs, and a signal is obtained where the frequency of only this band is shifted. Thus, the degradation of tone quality and the influence upon the harmonic structure are reduced and the device is simplified. |
