Vowel onset marker based objective evaluation of Japanese phonemic length contrast produced by non-native speakers

Abstract

Aiming at an objective evaluation of second language (L2) learner's Japanese timing control, this study proposes an objective measure to predict a subjective measure of L2 speakers' production given by Japanese native evaluators from the view point of goodness of production. The focus here is on phonemic length contrast, e.g., /kako/ "the past" versus /kakko/ "parentheses" and /kaze/ "wind" versus /kaze:/ "taxation" which is difficult for L2 learners particularly when incorporated with speaking rates. In this present study proposed an objective measure using a vowel onset time marker as a key perceptual and psychoacoustic marker to normalize speaking rate variations. The proposed new measure reflects tempo normalization between L2 learners by dividing the proficiency of mora-timing control in production. The experimental results show that both vowel length contrast and consonant length contrast have a significantly higher correlation with the subjective evaluation score in which the coefficient was stable than using a simple duration difference measure. These results suggest that applying the psychoacoustic parameters would be effective to build up an objective evaluation of L2 learners. © 2013 Acoustical Society of America.