An Investigation of Non-Uniform Error Cost Function Design in Automatic Speech Recognition

The classical Bayes decision theory [3] is the foundation of statistical pattern recognition. In [4], we have addressed the issue of non-uniform error criteria in statistical pattern recognition, and generalized the Bayes decision theory for pattern recognition tasks where errors over different classes have varying degrees of significance. We further introduced the weighted minimum classification error (MCE) method for a practical design of a statistical pattern recognition system to achieve empirical optimality when non-uniform error criteria are prescribed. However, one key issue in the weighted MCE method, the methodology of building a suitable non-uniform error cost function given the userpsilas requirements, has not been addressed yet. In this paper, we propose some viable techniques for the design of the non-uniform error cost function in the context of automatic speech recognition (ASR) according to different training scenarios. The experimental results on the TIDIGITS database [8] are presented to demonstrate the effectiveness of our methodologies.