Two stage utterance verification device and method thereof in speech recognition system

A method for two stage utterance verification method, comprising the steps of:

• a) performing a first utterance verification function based on a support vector machine (SVM) pattern classification method by using feature data inputted from a search block of a speech recognizer;
• b) determining whether a confidence score, which is a result value of the first utterance verification function, is a misrecognition level for deciding rejection of a speech recognition result;
• c) performing a second utterance verification function based on a classification and regression tree (CART) pattern classification method by using heterogeneity feature data including meta data extracted from a preprocessing module, intermediate results from function blocks of the speech recognizer and the result of the first utterance verification function when the speech recognition result is accepted by the first utterance verification function, and returning when the speech recognition result is rejected by the first utterance verification function;
• and
• d) determining whether the speech recognition result is misrecognition based on a result of the second utterance verification function, transferring the speech recognition result to a system response module when the speech recognition result is accepted by the second utterance verification, and returning when the speech recognition result is rejected by the second utterance verification.