Leveraging back-off grammars for authoring context-free grammars
View Patent ↗A system and method of refining context-free grammars (CFGs). The method includes deriving back-off grammar (BOG) rules from an initially developed CFG and utilizing the initial CFG and the derived BOG rules to recognize user utterances. Based on a response of the initial CFG and the derived BOG rules to the user utterances, at least a portion of the derived BOG rules are utilized to modify the initial CFG and thereby produce a refined CFG. The above method can carried out iterativey, with each new iteration utilizing a refined CFG from preceding iterations.
1. A speech recognition method comprising:
recognizing, by a processor, a user utterance using a context-free grammar (CFG) as a language model;
identifying, by the processor, out-of-grammar (OOG) utterances that are not recognizable by the CFG;
processing, by the processor, the OOG utterances through a back-off grammar (BOG) that is derived from the CFG and that includes a plurality of BOG rules;
collecting statistics related to a degree of success of the plurality of BOG rules in processing the OOG utterances and statistics related to a frequency of each of the plurality of BOG rules being considered a top recognition result;
utilizing a dictation grammar to selectively transcribe a portion of the OOG utterances based at least in part on the collected statistics; and
incorporating the transcribed portion of the OOG utterances into the CFG.
2. The method of claim 1 wherein the transcribed portion of the OOG utterances is automatically incorporated into the CFG.
3. The method of claim 2 and further comprising repeating the steps of claim 2 iteratively until an acceptable speech recognition efficiency level is reached.
4. The method of claim 1 and further comprising saving the portion of the OOG utterances as file copies.
5. The method of claim 4 wherein the portion of the OOG utterances are saved as .wav files.
6. The method of claim 1 wherein the transcribed portion of the OOG utterances is manually incorporated into the CFG.