Prolatio is the fourth stage of musical notation established in the quantitative system of the 14th century Ars Nova. It uses fine tremolo as the main motive, and by combining and mixing various instruments with different sound principles, it creates a variety of perspectives and colors. Premiere: December 12, 1990, Art Lespiran's 5th Concert "Chamber Music - A Perspective on the New Century II", Tsuda Hall (Tokyo) Revised premiere: July 17, 1992, Kita-Topia Chamber Music Concert, Art Lespiran Concert, Kita-Topia Sakura Hall (Tokyo)