14. A speech recognition method as claimed in claim 13, further comprising the steps of: storing at least one acoustic silence model representing one or more series of acoustic feature values representing the absence of a spoken utterance; generating a match score for each sound and the acoustic silence model, each match score comprising an estimate of the closeness of a match between the acoustic silence model and a series of feature signals corresponding to the sound; and characterized in that the recognition threshold score for the current sound is equal to the first confidence score (a1) if the match score for the prior sound and the acoustic silence model is greater than a silence match threshold, and if the prior sound has a duration exceeding a silence duration threshold, or (a2) if the match score for the prior sound and the acoustic silence model is greater than the silence match threshold, and if the prior sound has a duration less than the silence duration threshold, and if the best match score for a second prior sound and an acoustic command model was greater than a recognition threshold for the second prior sound, or (a3) if the match score for the prior sound and the acoustic silence model is less than the silence match threshold, and if the best match score for the prior sound and an acoustic command model was greater than a recognition threshold for the prior sound; or the recognition threshold for the current sound is equal to the second confidence score better than the first confidence score (b1) if the match score for the prior sound and the acoustic silence model is greater than the silence match threshold, and if the prior sound has a duration less than the silence duration threshold, and if the best match score for the second prior sound and an acoustic command model was less than the recognition threshold for the second prior sound, or (b2) if the match score for the prior sound and the acoustic silence model is less than the silence match threshold, and if the best match score for the first prior sound and an acoustic command model was less than the recognition threshold for the prior sound.
15. A speech recognition method as claimed in claim 14, characterized in that the recognition signal comprises a command signal for calling a program associated with the command.