INVESTIGATIONS INTO VOWEL AND CONSONANT STRUCTURES IN ARTICULATORY AND AUDITORY SPACES USING LAPLACIAN EIGENMAPS

Many studies have investigated the relationship between the articulatory and auditory features for isolated speech sound and vowels. For fully understanding the mechanisms of speech production and perception, it is necessary to investigate the consonants in the same way. For this reason, in this study, we investigate the manifolds of vowels and consonants out of Japanese reading speech using Laplacian eigenmaps. We constructed uniform articulatory and auditory spaces based on the vowels and consonants to investigate their manifolds. It is found that the distribution of consonants in articulatory space could be classified into labial and lingual groups which reflected their articulatory properties, while in auditory space their distribution was clustered according to voiced and unvoiced, plosive and fricative properties. In vowel-consonant acoustic space, the consonants distributed as a hoe-like shape, with voiced consonants located on the blade of the hoe and fused with vowels. We defined average correlation coefficients to measure the similarity of manifold between three speakers. The results indicated that the vowel/consonant structures had high consistency among the three speakers.