日本語母音, 子音調音の隣接音の影響による変動

抄録

Articulatory movements in the production of the VCV and CVC sequences in Japanese were observed by the x-ray microbeam method, and the contextual variations in the articulations of the middle vowels and consonants were examined. Speech materials examined were the meaningless words of the types /C_1VC_2ae/ (V=i, e, a, o, u ; C_1, C_2=m, t, k, s) and /mV_1CV_2ai/ (V_1, V_2=i, e, a, o, u ; C=m, t, k). It was observed that perturbations of vowel articulations by the consonantal context resulted in a large ovelap in the range of variations of tongue configurations between the vowels /a/ and /o/. The range of variation of the vowel /u/ also partly overlapped with that of /a/ and /o/. However, the differences in the positions of jaw and lip were consistently maintained among these vowels. For the vowels /i/ and /e/, there was consistent difference in the positions of tongue blade. The distinction between the front vowels and the other vowels was always clearly observed. It was also observed that, in the CVC sequences, the perturbations of vowel articulations by the preceding consonants were greater than those by the following consonants, regardless of the types of the vowels. In the VCV sequences, the variation in consonant articulations caused by the following vowels were greater than those by the preceding vowels. This asymmetric effect was clearly observed in case of /k/ but was smaller in other consonants.