Substitutions

My experimental sound work Substitutions is inspired by the Chinese lithophone in the RISD Museum’s Asian art collection. Lithophones are ancient instruments, stones that vibrate and produce sound when struck. The RISD Museum’s lithophone, an inverted L-shaped jade chime, or qing, dates from 1761-1762.

The first qing were likely adapted from agricultural ploughshare stones and used for signaling over distances to mark time, summoning people, and sounding warnings. These lithophones date back to at least 400 BCE, but were likely invented during Neolithic times. Later, these stones were arranged for ritual court music in pitch-ranged sets of 12, 16, or 32. According to the inscriptions on the Museum’s lithophone, it is the pitch nanlu¨, the 10th stone in a set of 12. In the second month of autumn, it would be used to mark the end of each musical movement during important ceremonies. Qing are traditionally played with a wooden mallet and use of either striking or tapping gestures. The long leg is known as the drum, and the shorter leg as the femur or thigh.

Leading up to the dissolution of the Qing Dynasty by 1912, musical instruments specific to court rituals fell out of use, and lithophone sets were broken up and sold. Today, jade Qing Dynasty chimes are scattered across private and public collections in the United States and elsewhere.

In early 2014, I viewed the Museum’s lithophone while it was in storage. The year before, I had been in Seoul, South Korea, working with players of the gayageum, a traditional zither-like string instrument, when I had my first experience with a comparable lithophone, the pyeongyeong on display at the National Gugak Center.

I was excited to learn about a similar historical stone in Providence, and about the opportunity to study it up close. Due to its status as a rare object, the stone had to be handled carefully and in a manner that was distant from its original use as a musical instrument. This circumstance prohibited listening to the stone, as this would require striking it percussively with a mallet. Unsatisfied that the sound was left to the imagination, I formed a plan in which I would compose a new musical work responding to the Museum piece. This was made possible by creating a granite replica which by design is for instrumental use and a prototype for continued research.

This lithophone is a close approximation to the Museum’s. The biggest differences are the material used (granite instead of jade) and the position of the bottom curve, a factor that may increase the duration of vibrations. Otherwise, original angles and measurements have been followed. The fabricated stone’s fundamental frequency is 690 Hz (near F5); this is not a match to the original, which according to scholarly literature should be near 440 Hz (A4). Differences were expected, however, given the different material.

In composing Substitutions, my aim has been to explore the stone chime as a percussive interface for computer-based sound synthesis and signal processing. In performance, a piezo transducer (a contact mic) is fixed to the stone’s vertex. This specialized transducer picks up the vibrations passing through the solid stone, rather than through the air.

The transducer’s signal is sent to custom software I created in the programming language Pure Data. In software, two computational substitutions take place.

First, the audio is analyzed in real-time for its frequency content, amplitude variations, and overall timbre. The data derived from this analysis is used to drive a procedure that recreates, or re-synthesizes, the source sound using a bank of sine-wave oscillators. The spectral information is used to produce drifting, sustained tones initiated by and fluctuating with percussive actions by the performer. The correspondences between action and sound are not one-to-one. Rather, resulting sounds from the performance gestures are scattered, lengthened, and diffused.

The second substitution is created via a process known as convolution reverb. Here I use prerecorded impulse responses to impart the acoustic characteristics of metallic percussion instruments onto the live audio signal. Thus, the perceived material quality of the stone is at times altered and shifting during the course of the performance.

To date, I have presented the work publicly on two occasions at the RISD Museum. On December 4, 2014, I gave a work-in-process demonstration for the celebratory launch of the Channel audio program. On February 26, 2015, I gave a premiere performance in conjunction with the RISD Faculty Biennial.

Looking to the months ahead, I will further refine the underlying system for Substitutions in preparation for a performance in June 2015 at the International Conference on New Interfaces for Musical Expression, the premier conference in designing human-computer interfaces and interactions for musical performance.

References

Terese Tse Bartholomew and Mitchell Clark, “The Walters Art Gallery 1764 Jade Qing Lithophone and Related Pieces,” Journal of the Walters Art Gallery 49/50 (1991/1992): 131-40.

Cheng-Yih Chen, Early Chinese Work in Natural Science : A Re-examination of the Physics of Motion, Acoustics, Astronomy and Scientific Thoughts. Hong Kong: Hong Kong University Press, 1996.

Amy S. Huang, “Jade Lithophone with Dragon Decoration,” Manual. http://risdmuseum.org/manual/159_jade_lithophone_with_dragon_decoration (accessed March 23, 2015).

Thomas D. Rossing, Junehee Yoo, and Andrew Morrison, “Acoustics of Percussion Instruments: An Update,” Acoustical Science and Technology 25(6) (2004): 406-12. doi: 10.1250/ast.25.406.

Kin-Woon Tong, “Shang Musical Instruments: Part One,” Asian Music 14(2) (1983): 17-182.

Junehee Yoo and Thomas D. Rossing, “Geometrical Effects on the Tuning of Chinese and Korean Stone Chimes,” Journal of the Acoustical Society of America 120(6) (2006): EL78-83. doi: 10.1121/1.2218983.

Thank you to RISD Museum, Hollis Mickey, Jeremy Radtke, and Northeast Marble, Granite, & Tile