Acoustic model creation method as well as acoustic model creation apparatus and speech recognition apparatus

An acoustic model creation apparatus to create a syllable HMM (Hidden Markov Model) which is an acoustic model, comprising:

• an initial phoneme-connected syllable HMM set generation device to combine phoneme HMMs trained in correspondence with individual phonemes, so as to generate an initial phoneme-connected syllable HMM set which includes initial phoneme-connected syllable HMM corresponding to individual syllables;
• and
• a HMM retraining device to retrain the initial phoneme-connected syllable HMM set so as to generate a phoneme-connected syllable HMM set being the acoustic model;
• a preliminary experiment device to conduct a preliminary experiment which uses training speech data, for a phoneme-connected syllable HMM set;
• a misrecognized-syllabic-part extraction device to check any misrecognized syllable and a syllable connected to the misrecognized syllable by using results of the preliminary experiment obtained by the preliminary experiment device and syllable label data prepared in correspondence with the training speech data, and to extract as a syllable connection, a combination between a correct answer syllable for the misrecognized syllable and a syllable connected to the misrecognized syllable;
• initial phoneme-connected syllable HMM/syllable-connected HMM set generation device to add a syllable-connected HMM which corresponds to the syllable connection extracted by the misrecognized-syllabic-part extraction device, into the phoneme-connected syllable HMM set, thereby generating an initial phoneme-connected syllable HMM/syllable-connected HMM set;
• the HMM retraining device to retrain the initial phoneme-connected syllable HMM/syllable-connected HMM set generated by the initial phoneme-connected syllable HMM/syllable-connected HMM set generation device, by using the training speech data and the syllable label data, thereby generating a phoneme-connected syllable HMM syllable-connected HMM set being the acoustic model;
• and
• characterized in that the misrecognized-syllabic-part extraction device counts the numbers of times of misrecognition of the syllable connections in the preliminary experiment results, and that, a syllable-connected HMM corresponding to any syllable connection whose number of times of misrecognition is at least a preset number, among the syllable connections extracted using the preliminary experiment results, is made a candidate for addition into the phoneme-connected syllable HMM set.