Speech recognition system with improved rejection of words and sounds not in the system vocabulary

摘要

A speech recognizer that selects a command model for a current sound if the best match score for the current sound exceeds its corresponding threshold score. The threshold score is assigned a confidence score based on the best match score and recognition threshold of a prior sound. When the best match score for the current sound exceeds a "poor" confidence score but is less than a "good" confidence score: (a) the word corresponding to the acoustic model having the best match score is accepted as highly likely to correspond to the measured sound if the previously recognized word was accepted as having a high likelihood of corresponding to the previous sound; (b) the word corresponding to the acoustic model having the best match score is rejected as highly unlikely to correspond to the measured sound if the previously recognized word was rejected as having a low likelihood of corresponding to the previous sound; or (c) if there is sufficient intervening silence between a previously rejected word and the current word, then the current word is also accepted as having a high likelihood of corresponding to the measured current sound.