The phonetic value of the devocalized vowel in Japanese - in case of velar plosive

This study investigates how the native speakers of Japanese tell the differences of the words containing the devocalized vowels. The close vowels [K? and =/? devocalize in Japanese when they are situated between voiceless consonants and between pause and voiceless consonant. In this paper, we verify the hypothesis that the devocalized vowels are the voiceless fricatives. =M KÀVVQ? =M /ÀVVQ? =M CVVQ? and =M QVVQ? were used for three experiments as the stimuli. The close vowels that follow the voiceless velar plosives devocalize in=M KÀVVQ? and =M /ÀVVQ?, on the other hand, the open vowels in =M CVVQ? and =M QVVQ? don't devocalize. The first experiment studied whether the native speakers of Japanese could distinguish the four stimuli. The second experiment studied whether the clue with which the native speakers of Japanese hear the differences of the words are the devocalized vowels or not. The stimuli of which the parts of the devocalized vowels were replaced with band limited noise were used. In the final experiment, the manipulated stimuli, in which the voiceless fricatives were inserted instead of the vowel. These results indicate that the parts of the devocalized vowel have the voiceless fricatives when the vowels follow the voiceless velar plosives, and that the native speakers of Japanese can hear the differences of the words containing the devocalized vowels through the differences of the values of the voiceless fricatives.