Grapheme based speech recognition

Abstract

Large vocabulary speech recognition systems traditionally represent words in terms of subword units, usually phonemes.This paper investigates the potential of graphemes acting as subunits.In order to develop context dependent grapheme based speech recognizers several decision tree based clustering procedures are performed and compared to each other.Grapheme based speech recognizers in three languages -English, German, and Spanish -are trained and compared to their phoneme based counterparts.The results show that for languages with a close grapheme-to-phoneme relation, grapheme based modeling is as good as the phoneme based one.Furthermore, multilingual grapheme based recognizers are designed to investigate whether grapheme based information can be successfully shared among languages.Finally, some bootstrapping experiments for Swedish were performed to test the potential for rapid language deployment.