Reference point alignment frequency warp method for speaker adaptation

The variations of speakers´ vocal tract shapes result in the variations of the formant positions and sequentially in the variances of the features extracted from every frame of speech. In order to remove or reduce the variations of the formant positions, a speaker adaptation method is proposed and investigated in this paper which is based on a frequency warp function (f.w.f.). The f.w.f. warps the frequency axis so that the variations can be reduced. For a given speaker, some frequency reference points are selected to help to get this f.w.f. by finding the relationship between the positions of these reference points before and after the warping. According to the new positions of those reference points for the given speaker, the f.w.f. can then be constructed. The experimental results show that this method reduces the error rate by an average of 14.5%