Multi-stage large vocabulary speech recognition system and method

Abstract

Multiple processing stages are provided with different vocabulary databases to improve processing time, efficiency, and accuracy in speech recognition. The entire vocabulary is divided into smaller vocabulary subsets, which are associated with particular keywords. A small vocabulary subset is generated or retrieved based on certain information, such as a calling party's locality. A user is prompted to provide input information, such as the locality in which a business whose phone number is requested is located, in the form of a spoken utterance to the system. If the utterance matches one of the entries in the initial small vocabulary subset, then the utterance is considered to be recognizable. If the utterance is not recognizable when compared to the initial small vocabulary subset, then the utterance is stored for later use. The user is then prompted for a keyword related to another subset of words in which his initial utterance may be found. A vocabulary subset associated with the received keyword is generated or retrieved. The initial stored utterance is then retrieved and compared to the newly loaded vocabulary subset. If the utterance matches one of the entries in the newly loaded vocabulary subset, then the utterance is recognizable. Otherwise, it is determined that the initial utterance was unrecognizable, and the user is prompted to repeat the initial utterance.