The recursive least-squares (RLS) algorithm has been used in the adapt
ive synthesis filter bank for fast convergence. However, because of in
terpolation operations involved in the synthesis process, fast RLS alg
orithms cannot be applied. In this Letter, an approach is proposed tha
t can formulate subband reconstruction as a multichannel filtering pro
blem. This formulation allows the application of fast multichannel RLS
algorithms and substantial reduction in computational complexity.