Acoustic-phonetic unit similarities for context dependent acoustic model portability

This paper addresses particularly the use of acoustic-phonetic unit similarities for portability of context dependent acoustic models to new languages. Since the IPA-based method is limited to a source/target phoneme mapping table construction, an estimation method of the similarity between two phonemes is proposed in this paper. Based on these phoneme similarities, some estimation methods for polyphone similarity and clustered polyphonic model similarity are investigated. For a new language, first a polyphonic decision tree is built with a small amount of speech data. Then, clustered models in the target language are duplicated from the nearest clustered models in the source language and adapted with limited data to the target language. Results obtained from the experiments demonstrate the feasibility of these methods.