HOWLING SUPPRESSING METHOD

摘要

PURPOSE:To suppress howling by examining the relativity between the present sound receiving signal and the past sound receiving signal of a microphone and lowering the gain of the frequency which is the reciprocal of a period when the strong relativity is continuously obtained. CONSTITUTION:A data holding circuit 11 retains only part of the specified period of the sound receiving signal of the microphone 10 and the retained data is renewed one after another. A relativity detection circuit 12 counts the relativity only in the specified period between the past sound receiving signal of the microphone and the present sound receiving signal of the microphone which are retained in the data holding circuit 11 and detects the period when the strong relativity is obtained. As for the detected period, how many times the period has been detected till the last time is examined and if the period is continuously detected M-times, it is decided that the howling occurs in the frequency which is the reciprocal number of the period and an equalizer circuit 13 is adjusted so as to lower the gain in the frequency. Thus the change of a transmission function for making a round from a speaker to the microphone can be followed and the howling can be suitable suppressed.