A new categorical factor analysis method is proposed and it is applied to investigate the influence of phonemic context on the distribution of vowel spectra. Conventional categorical factor analysis methods, such as quantification theory, assume that the influence of multiple categories are expressed by the linear combination of that of single category. In our method, the theory is modified to deal with nonlinear factor. Using this method, the multiple correlation coefficients are improved by 3.6 - 7.8 % as compared with the conventional linear method and some nonlinear categorical factors which affect the vowel distribution became apparent.
Bibliographic reference. Kobayashi, Tetsunori / Matsuda, Toshiyuki / Watanabe, Kazuhiro (1989): "Contextual factor analysis of vowel distribution", In EUROSPEECH-1989, 2277-2280.