SPEECH RECOGNITION METHOD WITH NOISE REDUCTION AND A SYSTEM THEREFOR

In a speech recognition system, a method for deciding an input pattern as one of reference patterns includes steps for calculating dissimilarities of the input pattern and the reference patterns and selecting a particular one of the dissimilarities which is lower than a threshold value. In order to reduce noise accompanying an input speech pattern in the input pattern, an average noise level is detected from an input pattern before the input speech pattern is detected and a noise factor is produced corresponding to the average noise level. The dissimilarities are multiplied by the noise factor to produce products and then the products are compared with the threshold value to recognize the input speech pattern. According to one aspect of the speech recognition system, particularly the system using the known clockwise DP matching with a beam search technique, the beam width factor is determined as a function of the noise level.