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Stereophonic teleconferencing provides more natural acoustic perception by virtue of its enhanced sound localization. Of paramount importance is stereo acoustic echo cancellation (SAEC) that poses a difficult challenge to low complexity adaptive algorithms to achieve acceptable AEC due, mainly, to the strong cross-correlation between the two-channel input signals. This paper proposes a transform domain two-channel lattice algorithm that inherently decorrelates the stereo signals. The algorithm, however, bears a high computational complexity for large filter orders, N. A low complexity O(4N) algorithm is developed based on employing the functionality of the two-channel lattice cell in the previous algorithm in a weighted subband scheme. The algorithm is capable of producing complete orthogonal subbands of the stereo signals, and also allows for a tradeoff between performance and complexity. The performance of the proposed algorithms is compared with other existing algorithms via simulations and using actual teleconferencing room impulse responses.
Date of Publication: Oct 2002