In practice, the part-of-speech (POS) information, capturing the syntactic role of words, has been widely used in clustering words (Wang and Vergyri, 2006;Maltese et al., 2001;Samuelsson and Reichl, 1999).
both Chinese characters and words are considered as model units in this study, and a word re-segmentation process on recognition hypotheses is necessary, where an n-gram language model based on word classes is adopted.