Structure-based prediction of English pronunciation distances and its analytical investigation

English is the only language available for international communication and is used by approximately 1.5 billions of speakers. It is also known to have a large diversity of pronunciation partly due to the influence of the speakers' mother tongue, called accents. Our project aims at creating a global and individual-basis map of English pronunciations to be used in teaching and learning World Englishes (WE) as well as research studies of WE [1], [2]. Creating the map mathematically requires a distance matrix in terms of pronunciation differences among all the speakers considered, and technically requires a method of predicting the pronunciation distance between any pair of the speakers. Our previous but very recent study [3] combined invariant pronunciation structure analysis [4], [5], [6], [7] and Support Vector Regression (SVR) effectively to predict the interspeaker pronunciation distances. In [3], very high correlation of 0.903 was observed between reference IPA-based pronunciation distances and the distances predicted by our proposed method. In this paper, after explaining our proposed method, some new results of analytical investigation of the method are described.