A method for selecting an optimum phoneme sequence using a posteriori probabilities of phonemes

A phoneme recognition system using phoneme discriminant filters was proposed, where segmentation and phoneme recognition were carried out simultaneously. However, the method had many phoneme insertion errors and often produced phoneme sequences that were inconsistent with Japanese phoneme connection rules. This paper proposes methods for reducing the number of phoneme insertion errors using inhibitory functions and for selecting an optimum phoneme sequence using dynamic programming based on the a posteriori probabilities of the phonemes. The definition of inhibitory functions is based on the Japanese phoneme connection rules and the phoneme duration information. This method was tested for the recognition of phonemes in a 212-work vocabulary uttered by ten male speakers. The inhibitory functions reduced the total number of phoneme insertion errors to 1/5 and, especially, reduced the number of consonant insertion errors. The a posteriori probabilities of phonemes were computed based on distributions of the output of the phoneme discriminant filters.