Towards a robust/fast continuous speech recognition system using a voiced-unvoiced decision

We show that the concept of voiced-unvoiced (VU) classification of speech sounds can be incorporated not only in speech analysis or speech enhancement processes, but also can be useful for recognition processes. That is, the incorporation of such a classification in a continuous speech recognition (CSR) system not only improves its performance in low SNR environments, but also limits the time and the necessary memory to carry out the process of the recognition. The proposed V-U classification of the speech sounds has two principal functions: (1) it allows the enhancement of the voiced and unvoiced parts of speech separately; (2) it limits the Viterbi (1967) search space, and consequently the process of recognition can be carried out in real time without degrading the performance of the system. We prove via experiments that such a system outperforms the baseline HTK when a V-U decision is included in both front- and far-end of the HTK-based recognizer.