Patent ID: 8259961

Claim:
An audio processing apparatus connected between a sound receiving device and a sound emitting device, the audio processing apparatus comprising: a signal processor that controls a volume of a sound signal provided to the sound emitting device; an adaptive filter that determines an adaptive signal so as to minimize a magnitude of an error signal; a subtractor that generates the error signal represented by a difference between the adaptive signal and an observation signal generated by the sound receiving device; a magnitude ratio calculator that calculates a magnitude ratio of the observation signal relative to the error signal or of the adaptive signal relative to the error signal for each frame that is sequentially segmented from the error signal along a time axis; and a controller that variably controls a gain of the volume of the sound signal according to the magnitude of the error signal when the magnitude ratio is less than a reference value, and that controls the gain of the volume of the sound signal so as to suppress an increase of the gain according to the magnitude of the error signal when the magnitude ratio is higher than the reference value.