Uniform speaker normalization using frequency-dependent scaling function

In this paper, we present improvements in the estimation of frequency-dependent scaling function for non-uniform speaker normalization when compared to the method in S. Umesh et al. (2002). Further, using the estimated frequency-dependent scaling function, /spl gamma/(f), we estimated the universal warping function that is necessary to separate out the speaker-dependent term as a translation factor and show that it is similar to mel-scale. Since, the proposed warping function is similar to mel-scale, we argue that our study "justifies" the usage of mel-scale in speech recognition, not only from the point of view of psychoacoustics but also from the viewpoint of speaker normalization. Finally, we have assumed the commonly used formula for mel-scale, mel = 2595 log/sub 10/1+f/700 for the universal warping function. In this paper, we have tried to fit a mel-like formula to the estimated universal warping function and use it to do non-uniform speaker normalization. We present the recognition results using these different universal warping functions with word error rate as the performance measure.