A modified CS-ACELP algorithm for variable-rate speech codingrobust in noisy environments

摘要

This letter deals with a variable bit-rate CS-ACELP speech codernbased on new algorithms that are robust in the presence of thenbackground noise typical of wireless communications. The coder presentsneight operating modes ranging from 0-8 kbit/s with an average bit-ratenof about 4 kbit/s. Subjective and objective comparisons with the recentnITU-T G.729 8 kbit/s standard, used in the discontinuous transmissionnmode, demonstrate that the proposed coder provides an average bit ratenreduction of about 20% maintaining the same algorithmic delay andnperceptive quality