Correspondence between the glottal gesture overlap pattern and vowel devoicing in Japanese

Correspondence between the glottal opening gesture pattern and vowel devoicing in Japanese was examined using PGG with special reference to the pattern of glottal gesture overlap and blending into the neighboring vowel. The results showed that most of the tokens demonstrated either a single glottal opening pattern with a devoiced vowel, or a double glottal opening with a voiced vowel during /CiC/ sequences as generally expected. Some tokens, however, showed a double glottal opening with a devoiced vowel, or a single glottal opening with a partially voiced vowel. From the viewpoint of gestural overlap analysis of vowel devoicing, an intermediate process of gestural overlap may explain the occurrence of the case in which the vowel was devoiced and showed a double phase opening. Nevertheless, the presence of a partially voiced vowel with a single opening phase clearly shows the complexity of vowel devoicing in Japanese, since there are possibly two different patterns of glottal opening (single phase and double phase), which could be observed in PGG analysis, in utterances with partially voiced vowels.