A four layer sharing HMM system for very large vocabulary isolated word recognition

This paper reports on a large vocabulary speaker independent isolated word recognizer targeting 50,000 words. The system supports a unique four-layer sharing structure for either continuous HMM or discrete HMM. Evaluation is performed using a dictionary of 5000 US city names, a dictionary of the 5000 English most frequent words, a dictionary of 50,000 English words, and the 110,000 word CMU English dictionary. For these dictionaries, recognition accuracy ranges from 90% to 93% for the top 3 results.