15. A speech recognition system for recognizing utterances belonging to a pre-established set of allowable candidate utterances, comprising: a. a visual feature extraction apparatus for converting signals representative of facial features associated with acoustic speech generation into a corresponding set of visual feature vector signals at uniform time intervals at its output; and b. a time delay neural network classifying apparatus connected to the output of the visual feature extraction apparatus, having means for generating a conditional probability distribution of the allowable candidate utterances from the set of visual feature vector signals produced by the visual feature extraction apparatus and generated over a prescribed interval of time.
16. The speech recognition system of claim 15 wherein the time delay neural network classifying apparatus comprises: a. a tapped delay line input layer for accepting a sequence of visual feature vectors and for providing a multiplicity of sequential visual vectors in parallel at the delay line output taps: b. a hidden layer of neural cells coupled to the output taps of the delay line for enhancement of time dependent features; c. a classification layer coupled to the output of the hidden layer neural cells for generating a set of output time varying signals each representative of the probability of its corresponding utterance being present; and d. an averaging layer apparatus, connected to the output of the classification layer, for generating a set of time averaged varying outputs, one for each allowable utterance type, representative of a conditional probability that the associated utterance was spoken.