Prosodic Analysis and Modeling of Nagauta Singing to Generate Prosodic Contours from Standard Scores

摘要

Nagauta is one of the classical styles of Japanese singing. It has very original and unique prosodic patterns, where abrupt and sharp changes of F_0 are often observed at mora (Japanese speech unit) transitions. This F_0 change is sometimes found even within a single mora. In this paper, we propose a model to synthesize this unique F_0 pattern by considering the abrupt and sharp changes as grace notes. Nagauta's original scores contain no strict descriptions of tones and durations. Therefore, the baseline melody realized in a performance depends on the singer and it is difficult to predict the baseline melody by looking only at the scores. In this paper, the baseline melody is explicitly given to a singer in the form of the standard notation and the singer is asked to sing the song in Nagauta style. By taking the standard score as input, the proposed model simulates the F_0 pattern generated by the singer under this condition. Further, this paper shows an interesting phenomenon about power movements at the sharp F_0 changes. Acoustic analysis of Nagauta singing samples reveals that the sharp increases of F_0 and the sharp decreases of power are synchronized. Although no discussion on physiological mechanisms of this phenomenon is done in this paper, another model is proposed to generate the unique power patterns. Evaluation experiments are done with young Japanese listeners and their results indicate high validity of the two proposed models.