ISCA Archive SPECOM 2004
ISCA Archive SPECOM 2004

A grapheme based speech recognition system for Russian

Sebastian Stüker, Tanja Schultz

With the increasing availability and deployment of speech recognition technology in real world environments fast and affordable adaptation of speech recognition systems to new languages and/or domains becomes more and more important. One of the most expensive components of a recognition system is the pronunciation dictionary that maps the orthography of the words in the search vocabulary onto a sequence of sub-units. Often phonemes act as such sub-units. Human expert knowledge is usually required for crafting the pronunciation dictionary, thus making it an expensive and time consuming task. Even automatic tools for creating such dictionaries often require hand labeled amounts of training material and rely on manual revision. In order to address the problem of creating a dictionary in a time and cost efficient way we have examined recognition systems at our lab that rely soly on graphemes rather than phonemes as subunits. The mapping in the dictionary thus becomes trivial, since now every word is simply segmented into its letters. Therefore no expert knowledge is needed anymore. Our experiments on different languages have shown that the quality of the resulting recognizer significantly depends on the grapheme-to-phoneme relation of the underlying language. Since Russian is a language with an alphabetic script with a fairly close graphemeto- phoneme relation it is very well suited to be a candidate for this approach. In this paper we present our results on creating a grapheme based Russian recognizer trained on the GlobalPhone corpus that covers fifteen different languages. We compare the performance of the resulting system to a phoneme based recognition system that was trained in the course of the GlobalPhone project, and compare the performance of two grapheme based systems whose context-dependent models were clustered with two different procedures.

Cite as: Stüker, S., Schultz, T. (2004) A grapheme based speech recognition system for Russian. Proc. 9th Conference on Speech and Computer (SPECOM 2004), 297-303

  author={Sebastian Stüker and Tanja Schultz},
  title={{A grapheme based speech recognition system for Russian}},
  booktitle={Proc. 9th Conference on Speech and Computer (SPECOM 2004)},