1. A speech recognition apparatus comprising: an acoustic processor for measuring the value of at least one feature of each of a sequence of at least two sounds, said acoustic processor measuring the value of the feature of each sound during each of a series of successive time intervals to produce a series of feature signals representing the feature values of the sound; means for storing a set of acoustic command models, each acoustic command model representing one or more series of acoustic feature values representing an utterance of a command associated with the acoustic command model. a match score processor for generating a match score for each sound and each of one or more acoustic command models from the set of acoustic command models, each match score comprising an estimate of the closeness of a match between the acoustic command model and a series of feature signals corresponding to the sound; and means for outputting a recognition signal corresponding to the acoustic command model having a best match score for a current sound if the best match score for the current sound is greater than a recognition threshold score for the current sound, the recognition threshold score for the current sound is equal to (a) a first confidence score if the best match score for a prior sound was greater than a recognition threshold for the prior sound, or (b) a second confidence score greater than the first confidence score if the best match score for the prior sound was less than the recognition threshold for the prior sound.
9. A speech recognition apparatus as claimed in claim 1, characterized in that the acoustic processor comprises a microphone.