Training Discriminative HMM by Optimal Allocation of Gaussian Kernels
Zhijie Yan, Peng Liu, Jun Du, Frank K. Soong, Ren-Hua Wang · 2006
Abstract. We propose to train Hidden Markov Model (HMM) by allocating Gaussian kernels non-uniformly across states so as to optimize a selected discriminative training criterion. The optimal kernel allocation problem is first formulated based upon a non-discriminative, Maximum Likelihood (ML) criterion and then generalized to incorporate discriminative ones. An effective kernel exchange algorithm is derived and tested on TIDIGITS, a speaker-independent (man, woman, boy and girl), connected digit recognition database. Relative 46–51 % word error rate reductions are obtained comparing to the conventional uniformly allocated ML baseline. The recognition performance of discriminative kernel allocation is also consistently better than the non-discriminative ML based, nonuniform kernel allocation. 1