Patent ID: 7962338

Claim:
A speech recognition apparatus comprising: a speech input unit that converts input speech into uttered speech data; a speech analysis unit that converts the uttered speech data into characteristic quantities; a recognition word dictionary that stores a plurality of recognition vocabulary words; a rejectable word dictionary that stores a plurality of rejectable vocabulary words; a speech verification unit that computes the degree of similarity between the input speech and the plurality of recognition vocabulary words stored in the recognition word dictionary using the characteristic quantities obtained through conversion by the speech analysis unit, computes the degree of similarity between the input speech and the plurality of rejectable vocabulary words stored in the rejectable word dictionary using the characteristic quantities obtained through conversion by the speech analysis unit, and, as a result of computing these degrees of similarity, extracts recognition vocabulary words with the highest degree of similarity from among the recognition vocabulary words as recognition candidates, and extracts rejectable vocabulary words with the highest degree of similarity from among the rejectable vocabulary words as rejection candidates; a first threshold value storage unit that stores a first threshold value used as a measure for rejecting the input speech; and a second threshold value storage unit that stores a second threshold value, which is greater than the first threshold value and is used as a measure for outputting the recognition candidates as a recognition result, wherein the speech verification unit outputs the recognition candidates as a recognition result, if the degree of similarity of the recognition candidates is greater than the second threshold value, and the speech verification unit, if the degree of similarity of the recognition candidates is smaller than the second threshold value, outputs the recognition candidates as a recognition result, when the degree of similarity of the recognition candidates is greater than the first threshold value and, at the same time, the degree of similarity of the recognition candidates is higher than the degree of similarity of the rejection candidates.