International Journal of Affective Engineering Vol.12 No.2 pp.309-315 (2013) Special Issue on KEER 2012 ORIGINAL ARTICLE Construction and Verification of the Scale Detection Method for Traditional Japanese Music – A Method Based on Pitch Sequence of Musical Scales – Akihiro KAWASE Department of Corpus Studies, National Institute for Japanese Language and Linguistics, 10-2 Midori-cho, Tachikawa City, Tokyo 190-8561, Japan Abstract: In this study, we propose a method for automatically detecting musical scales from Japanese musical pieces. A scale is a series of musical notes in ascending or descending order, which is an important element for describing the tonal system (Tonesystem) and capturing the characteristics of the music. The study of scale theory has a long history. Many scale theories for Japanese music have been designed up until this point. Out of these, we chose to formulate a scale detection method based on Seiichi Tokawa’s scale theories for traditional Japanese music, because Tokawa’s scale theories provide a versatile system that covers various conventional scale theories. Since Tokawa did not describe any of his scale detection procedures in detail, we started by analyzing his theories and understanding their characteristics. Based on the findings, we constructed the scale detection method and implemented it in the Java Runtime Environment. Specifically, we sampled 1,794 works from the Nihon Min-yo Taikan (Anthology of Japanese Folk Songs, 1944-1993), and performed the method. We compared the detection results with traditional research results in order to verify the detection method. If the various scales of Japanese music can be automatically detected, it will facilitate the work of specifying scales, which promotes the humanities analysis of Japanese music. Keywords: Traditional Japanese music, Theory of Musical Scales, Tonesystem composers, musicians, song pieces, or how the audience 1. INTRODUCTION interprets musical experiences, in terms of the art music of the common practice periods identified as Baroque, 1.1 Purpose of the study Classical and Romantic in Western Europe. However, The main purpose of this study is to partially express the there is also an undeniable sense that many aspects of concept of Japanese music by estimating the structures musical structure may play an important role in non- from folk songs. Western music as well, and research achievements from A scale is a series of musical notes in ascending or many practical fields have not yet utilized or led to stud- descending order, which is an important element for ies of ethnomusicology [6]. Thus, the question “How did describing the structure (the tonal system, Tonesystem) non-Western cultures conceptualize their own music?” and capturing the characteristics of the music [1]. remains unsolved. In addition, methods in the field of A fundamental aspect of musical analysis and folk song comparative musicology integrate fieldwork in cultural research is to clarify the scale in a musical piece [2]. anthropology and document investigation in historical Many scale detection models have been developed. For science based on a humanities approach [7]. In this instance, a method for tracing chord progressions of respect, there have been many case studies about non- Western music was developed based on Noam Chomsky’s Western music from a musicological point of view, but generative grammar [3-4], and discriminating tonality of those studies were conducted with a small amount of Japanese music was developed based on Japanese yona data, and have rarely been reconfirmed by objective nuki musical scales (extracting the fourth and the analysis utilizing large amounts of data for computa- seventh note from heptatonic scales) [5]. However, a tional analysis. detection model that encompasses the essence of tradi- If the various scales in Japanese music can be tional Japanese music has not yet been developed. automatically detected, it will facilitate the work for Traditionally, in the fields of cognitive science and specifying scales, which people have traditionally done music analysis that use computer-based technologies, by hand, and will promote the humanities analysis of researchers have mainly been concerned with specific Japanese music. We will start by implementing the scale Received 2012.12.23 Copyright © 2013 Japan Society of Kansei Engineering. Accepted 2013.01.18 309 All Rights Reserved. International Journal of Affective Engineering Vol.12 No.2 detection method [8], and then verify its validity by using Chinese music theory and Gong in Japanese music theory it on the music corpora of Japanese folk songs. represent the same pitch height, although the terms are different. 1.2 Organization Although the Japanese adopted many musical terms This paper is organized as follows. In Section 2, we from the original Chinese, these terms were pronounced will first look at the major scale theories in Japanese differently in Japan. For descriptive purposes, here we music to summarize important concepts and terms related will use {C, D, E, G, A (, C)} instead of {Gong, Shang, to scale detection method. Based on this understanding, Jue, Zhi, Yu (, Gong)} according to the equivalent of Section 3 outlines the basic principles of Seiichi Tokawa’s moving the C note around the 12 pitches of the Western scale theories. Section 4 gives an outline of our scale scale. detection method with an experiment of how a scale of the national anthem of Japan can be detected. Section 5 2.2 In (Yin) scale and Yo (Yang) scale gives an overview of the musical data used for verifying In the Meiji period (1868-1912), in his book Zokugaku the detection method. Then, in Section 6, we implement Senritsu Ko (On the Melodies of Japanese Vernacular the detection method and apply to the musical data. We Music) [11], a musicologist Rokushiro Uehara classified compare the detection results with traditional research the native songs into two types: the In scale (In mode results, and discuss the validity of the detection method. or Miyako-bushi scale) and the Yo scale (Yo mode or In Section 7, we conclude the paper by summarizing the Inaka-bushi scale). Uehara’s greatest contribution is that whole study and describing future topics. he approximated the ancient Chinese pitches with the 12 Western chromatic semitones, which made it possible to 2. SCALES THEORY IN JAPANESE MUSIC express the melodies of Japanese music on Western staff notation. However, there were many difficulties in In the 12th century, music and musical instruments, as explaining all Japanese music using the two scales, the In well as Buddhism and Confucianism, were originally scale and the Yo scale. Many scholars, including Shuji introduced from China, which developed independently Isawa, the first Chief of the Education Bureau of Japan, into Japanese music. Since there was a strong tendency brought counterarguments during the last half of the to focus on individual songs or playing styles instead Meiji period to the first part of the Showa period of theoretical aspects, Japanese music did not have a (1926-1989). theoretical system until Western music was imported as a part of the Europeanization policy during the Meiji period 2.3 Koizumi’s tetrachord theory (1868-1912) [9]. Influenced by the methods of Western comparative musicology, Fumio Koizumi conceived of a scale based 2.1 Ritsu scale and Ryo scale on the interval of a perfect fourth, and has developed his It is considered that the musical scales brought from tetrachord theory [12]. As shown in Figure 1, a tetrachord China during the time from the Nara period (710-794) to is a unit consisting of two stabled outlining tones called the Heian period (794-1185), were roughly classified into kaku-on (nuclear tones or Kernton), and one unstable two groups: the Ritsu scale and the Ryo scale. In the scale intermediate tone, four different types of tetrachords can theory of ancient China, {Gong, Shang, Jue, Zhi, Yu be formed: the Min-yo, the Miyako-bushi, the Ritsu, and (, Gong)} were given to each pitch of the scale as a unique the Ryu-kyu. name. Also, any of these five pitches can be cyclically Koizumi suggested that combinations of two identical shifted as a tonic (first pitch of a scale), which will gener- tetrachords with an intermediate tone generate a one of ate five different scales. Although the name of the tonic four Japanese scales named after each tetrachord: the was not replaced in China, the tonic was always read as Min-yo scale, the Miyako-bushi scale, the Ritsu scale, and Gong in Japan. It became customary to allocate Gong to any tonic in Japanese scale theory [10]. For example, in a scale in which Shang is placed on the tonic, the names of each pitch would become {Shang, Jue, Zhi, Yu, Gong (, Shang)} in Chinese music theory, while {Gong, Shang, Jue, Zhi, Yu (, Gong)} is universally applied in Japanese music theory. In this case, Shang in Figure 1: Koizumi’s four basic tetrachords 310 International Journal of Affective Engineering Vol.12 No.2 Construction and Verification of the Scale Detection Method for Traditional Japanese Music the Ryu-kyu scale [12]. In addition, combinations of Miyako-bushi scale, Ritsu scale, and Ryu-kyu scale corre- different tetrachords (conjunct and disjunct) can also be spond to Tokawa’s Yo-type A-mode, In-type E-mode, consisted to generate a new scale [13]. Yo-type G-mode, and Ryu-kyu-type C-mode, respectively. Since Tokawa’s theory is not based on the tetrachord 3. TOKAWA’S SCALE THEORIES theory, there is criticism that Tokawa’s classification cannot capture the fundamental features of Japanese 3.1 Four major types of Tokawa’s musical scales music. However, Tokawa’s theory still provides a versatile Seiichi Tokawa, a Japanese music theorist, criticized system which covers various conventional scale theories that the problem with scale theory in Japanese music is under the present circumstances.