Simple fast vector quantization of the line spectral frequencies

The authors propose a simple fast-search VQ of the LSFs to be used on top of the split VQ, that is, in each of the sub-vector domains. The main trait of the proposed method is that no suboptimal codebooks are used and there is no further reduction in performance. In each sub-vector domain, a full-size optimally trained codebook typically of size 1024, is searched using a fast-search algorithm. The result of this search is identical to that of a full-search, yet, only about 25% of a full-search complexity is needed