COMPARISON OF PITCH PREDICTION AND ADAPTATION ALGORITHMS IN FORWARD AND BACKWARD ADAPTIVE CELP SYSTEMS

The paper examines several pitch estimation and adaptation algorithms in forward and backward adaptive CELP systems. The authors compare ope n-loop and closed-loop pitch estimation structures, the use of integer and non-integer delay pitch prediction, and the implementation of blo ck adaptive and sample recursive pitch tracking algorithms. Forward ad aptive systems are found to perform better with a closed-loop structur e in conjunction of non-integer delay pitch prediction. However, tempo ral and noise feedback problems suggest that open-loop structures with hybrid pitch tracking are better suited for backward adaptive systems .