Audio amplification apparatus with howling canceler

摘要

In an audio amplification apparatus connected to a microphone and a speaker, an audio amplification circuit amplifies an audio signal and inputs the amplified audio signal to the speaker. A howling canceler has an adaptive filter which is set with a filter coefficient based on the audio signal input to the speaker and a residual signal so as to simulate a feedback transmission path from the speaker to the microphone such that the adaptive filter processes the audio signal to produce a simulation signal. The residual signal is obtained by subtracting the simulation signal from an input audio signal inputted from the microphone and fed to the audio amplification circuit. An internal sound source generates the audio signal and inputs the audio signal to the speaker. A sound source determination portion determines whether or not the input audio signal contains an external audio signal provided from an external sound source other than the audio signal fed back from the speaker to the microphone, and controls update of the filter coefficient in accordance with a result of the determination.