A static lexicon network representation for cross-word context dependent phones

Abstract

To cope with the prohibitive growth of lexical tree based search-graphs when using cross-word context dependent (CD) phone models, an efficient novel search-topology was developed. The lexicon is stored as a compact static network with no language model (LM) information attached to it. The static representation avoids the cost of dynamic tree expansion, facilitates the integration of additional pronunciation information (e.g. assimilation rules) and is easier to integrate in existing search engines. Moreover, the network representation also results in a compact structure when words have alternative pronunciations, and due to its construction, it offers partial LM forwarding at no extra cost. Next, all knowledge sources (pronunciation information, language model and acoustic models) are combined by a slightly modified token-passing algorithm, resulting in a one pass time-synchronous recognition system.