Patent ID: 8107617

Claim:
An audio processor of a loud speech communication system including a speaker and a microphone, the audio processor comprising: an adaptive filter wherein an amount of update in a learning event is set to an arbitrary value, and a filter coefficient is serially determined corresponding to the set amount of update; a semi-fixed filter adapted to an echo cancellation process of an audio input signal input from the microphone; adaptive filter assessment means that calculates a length of an update vector based on the filter coefficient determined by the adaptive filter and a length of an update vector based on a filter coefficient set in the semi-fixed filter and that performs assessment of the filter coefficients by comparing the lengths of the update vectors; and coefficient specifying means that sets an optimal filter coefficient, from among the filter coefficients assessed by the adaptive filter assessment means, into the semi-fixed filter in according to a result of the assessment of the filter coefficients performed by the adaptive filter assessment means.