Weaver SSB subband acoustic echo canceller [videoconferencing application]

A Weaver SSB subband structure is used to implement an acoustic echo canceller. The structure has 29 bands of 250 Hz width, covering the audio range from 0 to 7 kHz. The Weaver structure lowers each band pass region to baseband, allows for oversampling to eliminate aliasing components, and is computationally efficient. The subsampled components are purely real, as compared to the complex components found in some other subband schemes. The adaptive filter update algorithm is a variant of the block NLMS. The double-talk, divergence, echo suppression, and noise fill-in algorithms all fully exploit the band pass structure to achieve performance difficult to attain in full-band or two-band acoustic echo cancellers. The acoustic echo canceller has been extensively field tested and has been shown to be robust