Discrimination Ability and Pronunciation Preference between Voiced and Devoiced Vowels by Native Japanese Speakers

Japanese vowel devoicing was investigated from the viewpoint of perception, an approach which has not been taken in any previous studies. It appears in some dialects of Japanese, including Tokyo dialect. Three tests, a vowel preference test, a same/different test, and an inter-stimulus interval effect test were performed. In the vowel preference tests, 46.3% of devoiced vowel dialects speakers and 41.2% of voiced vowel dialects speakers could discriminate between devoiced and voiced vowels. These percentages were lower than expected in general. The same/different test resulted in a similar percentage. Moreover, in the short interstimulus interval, although we expected that the percentage of subjects who could discriminate would increase, on the contrary it decreased. From these results, it appears that vowel devoicing might not be necessary for Japanese pronunciation.