A Study on the Timbre of the Piri Focusing on Yoseong Sound

Transcription

1 , pp A Study on the Timbre of the Piri Focusing on Yoseong Sound Sangbong Nam 1, Sun-jin Lee 2, Gangseong Lee 3, and Donoung Lee 4* 1 Seoul National University, sangbongnam@gmail.com 2 Seoul National University, sun-jin.lee@hotmail.fr 3 Gwangwoon University, gslee0115@gmail.com 4* Seoul National University, dolee@snu.ac.kr Abstract. Yoseong sound is one of the piri s representative techniques including unique timbre of a Korean traditional musical instrument. This paper presents acoustic characteristics of yoseong sound by analyzing sound of the piri. We expect that results of this study can be applied to the Hybrid physical modeling of the piri. Keywords: Piri, Yoseong, Sound Analysis, Sound Synthesis 1 Introduction A number of studies have been researched to imitate the sound of musical instruments by utilizing music synthesizers since These music synthesizers can be divided into two broad categories: functional synthesizers and sampling synthesizers. To maximize reality of sound, hybrid ways of mixing these two techniques of sound synthesis have been researched in recent years [1]. One of the ways, so called hybrid physical modeling, is in progress at the Center for Arts and Technologies at Seoul National University [2] and this paper is as part of it. In this article, we shall describe to combine realistic sound quality of sampling with the performance interaction of functional synthesis using sound of the piri, a Korean double reed instrument. The sampling sound of the piri will be analyzed to know the character of the piri sound and an expressive technique, yoseong. Many kind of software such as Praat [3], AudioSculpt [4], SPEAR [5], Python [6], and Max [7] were used to analyze sounds. 2 Structure of the Piri The piri is a Korean double reed instrument of the piri family. There are eight finger holes on the bamboo body. Seven of the finger holes are on the front and one is on the back for the thumb. There are four types of the piri depending on a style of music and use: Hyang piri, Se piri, Dang piri, and Dae piri. Because of its popularity, The sound of the hyang piri was chosen for the study. Structure of the piri can be divided into two sections, double reed and stopped-cylindrical pipe, as Fig. 1. ISSN: ASTL Copyright 2014 SERSC

2 Fig. 1. Structure of Piri 3 Acoustics of the Piri The piri and the clarinet have a similar structure as a stopped-cylindrical pipe, which has an acoustics feature that the energy of the even number in overtones are noticeably week. Fig. 2 shows this character in the clarinet. The second and forth harmonics are barely distinguishable. The oboe, which is known as the most similar instrument with the piri because of its double reed, is not a stopped-cylindrical pipe, but a conical pipe. Fig. 3 presents a harmonic structure in the oboe. The amplitude of the second and third overtones are higher than the fundamental tone. Fig. 2. Harmonics of the clarinet[8] Fig. 3. Harmonics of the oboe[9] Fig. 4 describes the harmonics of the piri analyzed by Praat software with 30 millisecond of the window length. The ordinary tone of the piri from Hz(C3) to Hz(F4) were recorded to analyze the sound. In the lower range from C3 to F3, the amplitudes of the fundamental and third overtone were higher than the amplitudes of the second and forth overtone. It means that sound of the piri presents the character of a stopped-cylindrical pipe. However, this acoustic character is disappeared above Gb3 in higher range of the piri sound. This is the phenomenon that could be also seen in the clarinet and Fig. 5[10] presents it. Although the second and forth overtones are almost invisible in D3, the fourth overtone is visible in D4, and it shows a completely different harmonic structure in G5. 66 Copyright 2014 SERSC

3 Fig. 4. Harmonics of the piri by range Fig. 5. Harmonics of the clarinet by range 4 Acoustics in Yoseong play Yoseong is a musical effect consisting of an alteration of pitch. It has been performed to add expressions to Korean traditional music. Although it is somewhat similar with vibrato in western music, the rate of change in two factors of the yoseong, the amount of pitch variation and the speed with which the pitch is varied, is very high that makes a difference from vibrato. Variations of pitch, amplitude, and harmonics in yoseong were analyzed in the same plot to know the relationship among those variables in Fig. 6. In the plot, broken lines vertically divide the graph when a slope of pitch passes an inflection point. There are couple of features in this plot. First, pitch and amplitude of a sound does not change with a same ratio. While pitch increases, amplitude increases and decreases. While pitch decreases, amplitude holds it in a low point. Another feature here is the relationship between harmonics and other parameters. The variations of the first, third, and fifth harmonics are proportional to the variation of amplitude. And the variations of the second and forth harmonics are inversely proportional to the variation of pitch. Copyright 2014 SERSC 67

4 Fig. 6. Variations of pitch, amplitude, and harmonics in Yoseong 5 Conclusion In this paper, we have analyzed a structure and timbre of the piri and its yoseong effect. The result of the analysis shows that the piri has acoustic properties of a double reed and a stopped-cylindrical pipe. Especially during yoseong play, it was figured out that not only the pitch, but also the amplitude and harmonics of the piri sound are altered with a relationship to each other. In the future, we want to design a filter to change the ordinary sound of the piri to the yoseong sound. Acknowledgements. This work was supported by the Korea Creative Content Agency(KOCCA) of the Ministry of Culture, Sports, and Tourism(MCST), project KOCCA HE1405-R Copyright 2014 SERSC

5 References 1. Lindemann, E.: Music synthesis with reconstructive phrase modeling, IEEE Signal Processing Magazine, pp. 80~91 (March 2007) 2. Sangbong Nam, Gangseong Lee, Rina Yoo, Donoung Lee: A Study on the Timbre of Daegeum by the Appearance of Cheong Sound, HCI Korea International Conference (Feburary 2014) B. H. Suits, Physics Department, Michigan Technological University, (copyright ) Rossing, T., Moore R., Wheeler, P., Wheeler: The Sicence of Sound, 3rd Edition, Addison Wesley Publishing, 257p (2002) Copyright 2014 SERSC 69