Patent ID: 7120582

Claim:
A method of expanding an effective active vocabulary of a speech recognition system, the method comprising: receiving an input user utterance using a speech recognizer to perform speech recognition on said user utterance to produce one or more recognition candidates, the speech recognition comprising comparing digital values representative of the user utterance to a set of acoustic models representative of an active vocabulary of the system, the set of acoustic models including models of words and models of word fragments, receiving the recognition candidates from the speech recognizer, and when a received recognition candidate includes a word fragment: determining whether the word fragment may be combined with one or more adjacent word fragments or words to form a proposed word included in a backup dictionary of the speech recognition system, wherein forming the proposed word includes using a spelling rule associated with the word fragment that causes the spelling of the proposed word to differ from a spelling that would result from merely concatenating the particular word fragment with the one or more adjacent word fragments or words; if the word fragment may be combined with one or more adjacent word fragments or words to form a proposed word included in a backup dictionary of the speech recognition system, modifying the recognition candidate to substitute the proposed word for the word fragment and the one or more adjacent word fragments or words used to form the proposed word; and if the word fragment may not be combined with one or more adjacent word fragments or words to form a proposed word included in a backup dictionary of the speech recognition system, discarding the recognition candidate.