18. A word recognition system as set forth in claim 16, further including word-end detector means operably interposed between said zero-crossing detector of said signal conditioning means and said binary feature vector extracting means for monitoring the zero-crossing count for the digital waveform signal and producing a signal output declaring an end of word condition whenever the average frequency of said zero-crossings exceeds an end point target zero-crossing frequency for a time duration longer than a predetermined reference time duration; and said word recognizing means including decision logic means having inputs for receiving the distance measures of each of said binary reference vector sequences and successively received binary feature vectors and the output from said word-end detector means as a precondition to providing a word recognition output.
16. A word recognition system for identifying a spoken word independent of the speaker thereof, wherein the spoken word is represented by an analog speech signal, said word recognition system comprising: signal conditioning means for receiving an analog input speech signal and producing a digital waveform signal as a sequence of rectangular waveforms of polarity signs alternating between plus and minus polarities, said signal conditioning means including a zero-crossing detector for counting the number of polarity transitions in the digital waveform signal to obtain a zero-crossing count for each frame of the digital waveform signal; memory means storing a plurality of binary reference templates of digital speech data respectively representative of individual words and comprising the vocabulary of the word recognition system, the vocabulary consisting of a relatively small number of words with each of the words included in the vocabulary being represented by a binary reference template defined by a predetermined plurality of binary reference vectors arranged in a predetermined sequence and comprising an acoustic description of an individual word in a time-ordered sequence, each of said binary reference templates corresponding to a word acoustically distinct from the other words included in the vocabulary; means operably coupled to said signal conditioning means for extracting binary feature vectors from said digital waveform signal based upon the time duration intervals between zero-crossings of the digital waveform signal; means operably associated with said binary feature vector extracting means for comparing each binary feature vector of said digital waveform signal with the corresponding binary reference vectors of each of said binary reference templates to provide a distance measure with respect to each of the binary feature vectors and the predetermined binary reference vector sequences defining acoustic descriptions of the respective words included in the vocabulary of the word recognition system; and word recognizing means for determining which one of the plurality of the binary reference templates is the closest match to said digital waveform signal representing said analog input speech signal based upon the distance measures of each of said binary reference vector sequences and successively received binary feature vectors corresponding to respective frames of the digital waveform signal.