Comparison of Vowel Structures of Japanese and English in Articulatory and Auditory Spaces

In previous work [1] we investigated the vowel structures of Japanese in both articulatory space and auditory perceptual space using Laplacian eigenmaps, and examined relations between speech production and perception. The results showed that the inherent structures of Japanese vowels were consistent in the two spaces. To verify whether such a property generalizes to other languages, we use the same approach to investigate the more crowded English vowel space. Results show that the vowel structure reflects the articulatory features for both languages. The degree of tongue-palate approximation is the most important feature for vowels, followed by the open ratio of the mouth to oral cavity. The topological relations of the vowel structures are consistent with both the articulatory and auditory perceptual spaces; in particular the lip-protruded vowel /UW/ of English was distinct from the unrounded Japanese /w/. The rhotic vowel /ER/ was located apart from the surface constructed by the other vowels, where the same phenomena appeared in both spaces.