A modified K-means clustering algorithm for use in isolated work recognition

Studies of isolated word recognition systems have shown that a set of carefully chosen templates can be used to bring the performance of speaker-independent systems up to that of systems trained to the individual speaker. The earliest work in this area used a sophisticated set of pattern recognition algorithms in a human-interactive mode to create the set of templates (multiple patterns) for each word in the vocabulary. Not only was this procedure time consuming but was impossible to reproduce exactly because it was highly dependent on decisions made by the experimenter. Subsequent work led to an automatic clustering procedure which, given only a set of clustering parameters , clustered patterns with the same performance as the previously developed supervised algorithms. The one drawback of the automatic procedure was that the specification of the input parameter set was found to be somewhat dependent on the vocabulary type and size of population to be clustered. Since a naive user of such a statistical clustering algorithm could not be expected, in general, to know how to choose the word clustering parameters, even this automatic clustering algorithm was not appropriate for a completely general word recognition system. It is the purpose of this paper to present a clustering algorithm based on a standard K-means approach which requires no user parameter specification. Experimental data show that this new algorithm performs as well or better than the previously used clustering techniques when tested as part of a speaker-independent isolated word recognition system. P I. INTRODUCTION ATTERN recognition techniques have been widely used in all aspects of speech recognition. However, the area which has depended most on pattern recognition techniques is that of pattern clustering to derive a set of speaker-independent templates for isolated word recognition. The problem here is straightforward. We are given a set of N word patterns, where each pattern is a single utterance of one particular word in the vocabulary, spoken (in general) by N different talkers, and our task is to cluster the N patterns into A4 clusters such that within each