Vector sum codebook structure for variable rate coding

Recent applications in integrated network and secure communication necessitate the development of flexible speech coding techniques under adverse channel conditions. The authors explore the vector-sum innovation codebook structure in conjunction with a dynamic bit allocation strategy to develop an efficient variable rate speech coding system. The design algorithms for optimizing the basic innovation codevectors are described. They propose a dynamic bit allocation using the threshold decision rule to emphasize the locally important phonetic features. Furthermore, the linear prediction parameters are efficiently quantized by exploiting the inherent ordering relationship among the line spectrum pair parameters