ACOUSTIC ECHO CANCELLATION USING A VARIABLE LENGTH ADAPTIVE FILTER

摘要

An audio conferencing system having a base station, a loud speaker and one or more microphones generally operates to receive a F.E. audio signal, play the signal, and to receive a N.E. audio signal at the microphone that includes the F.E. audio signal modified by an echo path and a N.E. audio signal. The base station includes an adaptive filter whose length is controlled to be variable depending upon activity detected at each of one or more filter elements comprising the adaptive filter.

主权项

1. A method for cancelling acoustic echo in a microphone signal in an audio system, comprising:
activating a selected number of a plurality of inactive filter elements comprising an adaptive filter; detecting a filter element activity parameter in a last one of the activated filter elements to be greater than a specified threshold value, and activating at least a next/additional one of the plurality of inactive filter elements; calculating an adaptive filter coefficient for each one of the plurality of active filter elements, and each of the active filter elements using the calculated adaptive filter coefficient and audio information in a sample of a far end audio signal to calculate an estimate of an acoustic echo in a microphone signal; and the adaptive filter subtracting a sum of the estimates of the acoustic echo calculated by each of the active filter elements from the microphone signal.