Vowel normalization by articulatory information

The differences of vowel sounds among speakers are mainly caused by the morphological differences and different speaking styles of each speaker. The traditional vowel normalization methods in acoustic space are mainly concerned with the variance of acoustic features. There is no information of articulatory space taken into account. This paper proposed an approach to normalize vowel spectra by using articulatory information. The articulatory information of this study is mainly related with morphological variations of speakers. By taking articulatory information into account, the normalization method will have clear physical meaning that which part of acoustic variations has been reduced. This paper proposed a vowel normalization framework by using Thin-plate spline method. Thin-plate spline method was applied to normalize formant frequencies of three Chinese vowels, and was compared with traditional acoustic normalization methods for evaluation. The results show that the variances among different subjects were reduced. Vowel diagrams indicate that this method outperforms other acoustic methods in keeping speakers specific characteristics.