Patent ID: 8625776

Claim:
A method of suppressing near-end audio acoustically coupled at a far-end and returned to the near-end in a conference, the method comprising: determining first energy output of near-end audio sent from a near-end conferencing unit to a far-end conferencing unit by filtering the near-end audio into the first bands and determining first energy outputs of each of the first bands; determining second energy output of far-end audio sent from the far-end conferencing unit to the near-end conferencing unit by filtering the far-end audio into the second bands and determining second energy outputs of each of the second bands; detecting a return of the near-end audio in the far-end audio by cross-correlating variations in the first and second energy outputs for each of the bands to one another at increments of time delay over a time delay range, determining the time delay having a greatest cross-correlation for all of the bands, estimating for each of the bands a ratio of the far-end energy to the near-end energy, determining a result by multiplying the near-end energy by the ratio, and determining whether the result is equal to the far-end energy, wherein the detected return is caused by the near-end audio sent from the near-end conferencing unit to the far-end conferencing unit being acoustically coupled at the far-end conferencing unit and returned as part of the far-audio sent from the far-end conferencing unit; and suppressing the detected return from output at the near-end conferencing unit.