In this paper we describe a newly developed assessment method of Japanese mora timing, which is the foundation of the rhythm of the Japanese language, based on the phonetic segment technique. In this technique time-spectral patterns of uttered speech are transferred to the phonetic segment labels every 8ms frame shift. First, we propose a consonant region and vowel region estimation algorithm based on the phonetic segment labels. Next, we calculate the mora length simply and accurately by the number of phonetic segment labels and evaluate the pronunciation of foreign students. Furthermore, by using the utterance data of Japanese students, we show that the permissible variation based on the type of each mora and adjacent mora differs. We claim that the proposed method of evaluating the validity of a foreign student's mora timing by using the mora length and the ratio of each mora length to the whole word length is effective.
