A keyword is recognized in spoken language by assuming a start of this keyword is at every sampling time. An attempt is then made to image this keyword onto a sequence of HMM statusses that represent the keyword. The best path in a presentation space is determined with the Viterbi algorithm; and a local confidence standard is employed instead of the emission probability used in the Viterbi algorithm. When a global confidence standard that is composed of local confidence standards downwardly crosses a lower barrier for the best Viterbi path, then the keyword is recognized; and the sampling time assumed as start of the keyword is confirmed.
Method for recognizing a keyword in speech