Howling remover having cascade connected equalizers suppressing multiple noise peaks

摘要

A howling prevention apparatus prevents a howling noise which is generated in a sound amplification system using a microphone and a loudspeaker. The howling prevention apparatus utilizes a plural number of first to n-th equalizers, which have a variable frequency response and which modulate an output of the microphone. A detector detects a frequency point at which a loop gain of the system reaches a peak while supplying a standard noise signal to the loudspeaker to produce a test sound and measuring the sound collected by the microphone through the series of the equalizers. A frequency response of the first equalizer is adjusted to suppress a noise peak at and around a frequency point detected by the detector. Then, a frequency response of the second equalizer is also adjusted to suppress a noise peak at and around another frequency point detected by the detector. Lastly, a frequency response of the n-th equalizer is adjusted by subsequently repeating the above setting procedure.