A Model-Based Connected Digit Recognition System Using Either Hidden Markov Models or Templates

Although a great deal of effort has gone into studying large vocabulary speech recognition problems, there remains a number of interesting, and potentially exceedingly important, problems which do not require the complexity of these large systems. One such problem is connected digit recognition, which has applications to telecommunications, order entry, credit card entry, forms automation, and data base management, among others. Connected digit recognition is also an interesting problem for another reason, namely that it is one in which whole word training patterns are applicable as the basic speech recognition unit. Thus one can bring to bear all the fundamental speech recognition technology associated with whole word recognition to solve this problem. As such, several connected digit recognizers have been proposed in the past few years. The performance of these systems has steadily improved to the point where high digit recognition accuracy is achievable in a speaker trained mode.