Multilingual speech recognition for flexible vocabularies

The paper addresses the problem of designing a speech recogniser for multilingual vocabularies. The goal of the research is twofold: future Interactive Voice Recognition (IVR) systems, like a speech activated flight information service, are likely to require multilinguality as a major feature; besides, a general language-independent phonetic inventory might be very useful in bootstrapping phonetic models for a new language for which insufficient training data are available. Metrics were introduced in order to measure cross-language phonetic dissimilarities, and a multilingual phonemic inventory was created. Experiments were run on a speech database including Italian (I), Spanish (S), English (E) and German (G) words. Results clearly show that it is possible to reduce the complexity of a multilingual phonetic recogniser by exploiting phonetic commonalities across different languages, without significant losses in WA for multilingual tasks with respect to single language recognition tasks.