Abstract
The present study deals with the relation between +VOT tendency in the voiced alveolar plosive /d/ in Japanese and the birth year of the speakers. According to the results of the acoustic analysis of /d/ at the word initial position, there exists a strong correlation between the +VOT tendency in /d/ and the birth year of the speakers. We can assume that a manner of production of /d/ at the word initial position has been changing over about 60 years among the speakers whose birth year ranges from 1933 to 1988. However, the results from the listening test suggest that +VOT tendency does not influence the perception of /d/ and /t/ of the word initial position.
