Successive orthogonalizations in the multistage CELP coder

The authors investigate three algorithms that orthogonalize codebooks in a multi-stage code excited linear prediction (CELP) speech coder. They carry out the same processing, a locally optimal modeling of the perceptual signal, but the computational costs differ. The authors show that the recursive modified Gram-Schmidt algorithm extra computational cost is less than the other two. An orthogonal codebook is defined a priori and the authors observe an equivalence to orthogonal transform coding. Three methods based on the Karhunen-Loeve transform for designing this codebook are compared. A partitioned shape-gain VQ is applied in the transform domain