| 摘要 |
PURPOSE:To reduce periphery noise and to realize a zoom effect by giving adaptive noise suppressing processing to a non-directivity microphone by refering to the output of the microphone and deciding the suppressing quantity of the periphery noise in accordance with a zoom control signal. CONSTITUTION:First and second microphones 1 and 2 are arranged at a proper interval and both of them are non-directional. Then, at the time of providing a delaying device 3 so as to set its delay time to be a value obtained by dividing the distance between the microphones 1 and 2 by a sound speed, the output of a reducer 4 becomes the output of a single directivity microphone provided with a directional dip point in the direction of a speaker. Then, the output of the reducer 4 becomes a periphery noise component to be inputted to an adaptive filter 7 and the output of the filter 7 is subtracted from the output of the properly-delayed microphone 1. When successively correcting the transmission function of the filter 7 and repeating it, the output of the filter 7 becomes the periphery noise component estimated from the output of the subtracter 4. Then, at the time of deciding the suppressing quantity in accordance with zoom control, periphery noise is reduced in accordance with environment to realize the acoustic zoom effect. |
