Realtime Viterbi Searching for Practical Telephone Speech Recognition Systems

This paper studies searching and pruning process of the telephone speech recognition system for Private Automatic Branch Exchange (PABX) to explore the possible problems encountered in applying speech recognition to telephone network and to prepare the necessary techniques for the practical telephone speech recognition systems. Experiment on a baseline system which uses semi-syllable based multisubtree decoding structure and a classical Viterbi beam search algorithm achieves 89.86% keyword accuracy rate. By employing the dynamic threshold method, the keyword accuracy can reach 93.48 %. By employing the 'speed up jumping strategy', we achieve a higher performance with 97.35 % in keyword accuracy.