A method of generating English pronunciation dictionary for Japanese English recognition systems

In this paper, we propose a method for generating a pronunciation dictionary—extracting typical pronunciations for each word from speech data uttered by Japanese speakers—as one approach to speech recognition targeting English speech uttered by Japanese speakers whose mother tongue is not English. This method includes three processes: a process in which English phoneme HMMs (Hidden Markov Models) are adapted to the speaker using English speech uttered by a Japanese speaker; a process in which English by a Japanese speaker is translated into an English phoneme series using a phoneme typewriter; and a process by which representative phoneme series are selected with a clustering technique from multiple phoneme series derived with respect to each word. We also propose a speaker adaptation method in a recognition phase. In this method, the phoneme HMMs are adapted to the target speaker with a phoneme label series that expresses the typical pronunciation extracted using the above method. Evaluation tests by continuous speech recognition with English speech data uttered by five Japanese speakers using a pronunciation dictionary generated from other five Japanese speakers' data were carried out. The result of the tests indicated that sentence recognition errors were reduced by 72% compared to using a dictionary for native speakers.