A. Field of the Invention
The present invention relates to methods and systems for accepting recognition results determined by a speech recognition system. More particularly, the present invention relates to methods and systems for accepting recognition results using generalized additive modeling.
B. Description of the Related Art
Speech recognition systems typically employ a recognition rejection method to prevent incorrect recognitions and detect out of vocabulary speech. Erroneously recognized speech may occur, for example, from an error in the system or because the user utters a word that is not in the system's vocabulary. Speech recognition systems prevent these errors by including a rejection classifier that is trained using a speech training set to recognize speech.
U.S. Pat. No. 5,097,509 (the '509 patent) discloses a rejection method and classifier for speech recognition. According to this method, the rejection classifier creates a histogram for each feature and then combines weighted versions of each histogram. From the weighted histogram data, the rejection classifier determines a probability value that indicates whether the recognition result should be rejected.
In the '509 patent, however, the rejection classifier must recalculate the histogram weights for each new application. This is burdensome when a large number of rejection features are used to increase the accuracy of the rejection classifier. Another problem occurs when the top number of matches contain words that are confusingly similar to one another. In this case, the confidence in the recognition result will be low since the recognition will be an arbitrary selection among the confusingly similar words. The method of the '509 patent, however, cannot detect when the top number of matches contain words that are confusingly similar to one another. Therefore, a rejection classifier is desired that can use a large number of rejection features and which can detect when the top matches contain confusingly similar words. Furthermore, a rejection classifier is desired that can combine additional features to increase rejection accuracy.