shō in new music: acoustic analysis and composition

This article has been translated from the original Japanese publication dated April 1, 2020, on Gagaku-Dayori Vol. 61.

  Awareness of the nature of our sound is crucial for musicians. Historically, exploration in the world of acoustics was essentially conducted in a predominantly subjective manner. Interpretations would be made with abstract and instinctive impressions. Sound by its’ nature is an unobservable phenomenon, an intangible sensation decaying towards silence. Thus, accurately and objectively analyzing auditory sounds is almost impossible. Nevertheless, with the rapid development of both hardware and software technologies, it is now possible to analyze audio signals in a variety of approaches.


  In the spring of 2019, I had an opportunity to participate in a joint research with composer and musicologist Iván Solano, conducting a full spectral analysis of the sounds of the shō. The purpose of our research was to record the sounds of each of the seventeen pipes of the instruments, traditional and non-traditional chords, as well as non-conventional performance techniques (the glissando, for example) , and to utilize the frequency analysis data for new compositions. We used AudioSculpt (IRCAM) as our audio analysis software. The conclusion was presented in Conférence performative de Chatori Shimizu et Iván Solano at Conservatoire de Strasbourg, France.

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Ivan Solano (left) and Author (May 2019)

  The project was initiated with the composition of Kotsu-Shichi ~Studies on light and movement~ by Solano in 2018. Written for shō and soprano saxophone, comprehensive data on the overtone distribution, as well as the acoustic properties of both instruments were essential to the progress of the work. Consisting of seven movements, this work portrays the libration of the moon, mainly through the two pitches of G# and C#, along with margins of disparity falling into the plus-minus 15 cents range. The two instruments begin on the same pitch (ref. first and sixth movement). Thereupon, the soprano saxophone gradually bends the sound to widen the microtonal pitch difference, depicting Solano’s imagery of light and darkness. Additionally, the work accentuates the sonorous texture of the interweaving sounds of the duo, by giving a relative flexibility in the time flow, seen in the notation suited for the chronometric time identity. See previous publication (Gagaku-Dayori Vol. 60 “Shō in New Music: Time Identity and Notation”) for more information on the chronometric time identity.

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Kotsu-Shichi ~Studies on light and movement~ (2018) © ivansolano.net

  Broadly speaking, audible sounds can be described with four basic properties: (1) frequency (pitch), amplitude (loudness), envelope (length), and timbre. For shō, the first three characteristics can be flexibly adjusted, within the range of the structural limitations of the instrument, as well as the competence of the performer. On the other hand as our sonograms demonstrate, the timbre of the shō is extremely uniform, irrespective of the pitch and loudness. One of the phenomena visible in the single tone spectrogram is that the second and fourth harmonics are relatively more noticeable compared to the other harmonics. Borrowing the words of sonologist Yasuyoshi Okura (1936-), a stark second harmonic “gives the fundamental tone clarity and brightness,” and the fourth “further radiancy to the fundamental tone,” which explains the bright and the transparent timbre of the shō. Furthermore, by playing chords, both traditional and non-traditional, the difference of frequency components between each single note produce a beat frequency.


  Solano points out two features from the single tone spectrogram. First, he draws a vertical line straight up from the head (the point when the sound is first heard) of the fundamental tone. Then, he draws the second straight line from the head of the fundamental tone, connecting all the heads of the harmonics seen above the fundamental tone. This, he describes, results in the two lines diverging into what looks like a “crocodile’s mouth”. This indicates that the overtones are sounding later in time than the fundamental tone, and that the higher the pitch of the fundamental tone, the longer the delay of each harmonic.


  In addition, many of the overtones located above 7,000 Hz have a gentle downward pitch bend behavior. “This is a phenomenon that is often seen in the spectrogram of wind instruments. Because of the effect of air pressure when producing sound, higher frequencies are pushed up, so it is possible to confirm a slight but higher sound than the expected harmonics, which shortly after converges to the usual harmonic pitch”, explains Solano. The diverging gaps in seen in the “crocodile’s mouth,” as well as the downward pitch bend phenomenon on the upper harmonics, are occurring in a time frame of a millisecond or less. Thus, it is extremely difficult to apply the information directly to composition and performance. “Humans can instantly perceive the sound they hear using intuition, so this data is crucial to understanding the nature of our sound,” Solano believes.


Spectrogram showing the harmonic components of Mo (F5)

  Since presenting our joint research data in Strasbourg, I have returned to Dresden to further study the spectrogram data that I have acquired, and to contrast the configuration of the soundwaves with the spectrograms of other musical instruments, consisting over a thousand sound sources from the sounds of commonly known instrumental techniques to non-conventional ones, such as a prepared piano using various materials. As a result, I have discovered that shō’s sonic characteristics closely resembles the frequency domain of a rubber-muted viola playing in sul ponticello.


  While as a composer-in-residence at Visby International Centre for Composers in Sweden in the summer of 2019, I used the data as reference to compose Mimi Spelunking for shō and viola. In the work, I utilized the contrasting technical characteristics of the two instruments; the shō, which players are unable to freely bend a pitch to another pitch, and the viola, which can comfortably and effortlessly glissando from a note to another. In addition, utilizing the spectral data mentioned above, the rubber-muted violist, playing in sul ponticello, commences on the same pitch as the shō, and unhurriedly widens the pitch difference with glissando to unleash the resultant tone. Mimi Spelunking was recorded in Tokyo by Naoyuki Manabe and Chihiro Tai, and the score and audio has been released from #Followmyscore on Youtube.

Mimi Spelunking (2019) © chatorishimizu.com

We can frequently witness the pursuit of “newness” in new music, and the praise for fresh and innovative ideas (the definition of “newness” is highly debatable, so I will not open that can of worms here). Although I do not wish to promote the importance of “newness” in new music more than what has been precedented, I do believe that knowing the nature of a sound brings us to a new frame of reference on how to cook the sonic materials into a compositional work.