Comparison of pitch prediction and adaptation algorithms in forward and backward adaptive CELP systems

Examines several pitch estimation and adaptation algorithms in forward and backward adaptive CELP systems. The authors compare open-loop and closed-loop pitch estimation structures, the use of integer and noninteger delay pitch prediction, and the implementation of block adaptive and sample recursive pitch tracking algorithms. Forward adaptive systems are found to perform better with a closed-loop structure in conjunction of noninteger delay pitch prediction. However, temporal and noise feedback problems suggest that open-loop structures with hybrid pitch tracking are better suited for backward adaptive systems.<>