Patent ID: 8917885
Filing Date: 2014-12-23
Classification: H04R

Abstract:
1. A howling preventing apparatus comprising: an input unit that inputs an audio signal; a noise generation unit that generates and outputs a pseudo noise; a superimposing unit that superimposes a component of a frequency of the pseudo noise output from the noise generation unit to the audio signal input by the input unit and outputs the superimposed signal to an amplifying system, the frequency being higher than a predetermined frequency; a correlation calculating unit that calculates a correlation value between the audio signal input by the input unit and the pseudo noise generated by the noise generation unit; a loop gain estimation unit that estimates a gain of a closed loop based on the correlation value calculated by the correlation calculating unit; a gain control unit that controls to suppress the gain of the audio signal based on the gain of the closed loop estimated by the loop gain estimation unit; and a frequency control unit that controls to change a number of times of calculating a correlation value by the correlation calculating unit in accordance with the gain of the closed loop estimated by the loop gain estimation unit.