Moon Ha

composer / performer / researcher

reciprocal response (2023-24)

When I started new_LOrk (New York University Laptop Orchestra), I planned to write a piece that I and my students could play together. I envisioned music that we could freely explore various sonic possibilities, yet still within a musical system where we could listen to each other and share musical ideas. reciprocal response was rooted in that initial inspiration.

At the beginning of designing this musical system, I considered using a feedback system utilizing piezoelectric microphone and exciter. However, over time, I modified the plan as I wanted to create tactile Music Interaction interfaces that my students can touch and create sounds more intuitively. I used two different types of ceramic piezoelectric elements, as shown in the above photos:

+The premiere by new_LOrk on February 3, 2024 at Reembodied Sound 2024 @ EMPAC, Troy, NY

The ceramic disc (on the left) is one that many musicians and artists commonly use because it is affordable and easy to implement. It is great for attaching to any surface or object, and with proper impedance matching, it can provide a quite good signal. Although the piezo disc can go inside water, the cylindrical one (on the right) provides better frequency responses. Specifically, its resonant frequency is around 30KHz, which is higher than the human hearing frequency, resulting in a flat response to what we can hear. Also, it means feedback due to the resonant frequency is not a concern.

Schematic for the buffer/preamp

Each of the handmade objects houses a large piezo disc, a circuit board for signal amplification, and controls for power and volume. TL 072 is my go-to for amplification. While commercial Piezo DI boxes are convenient, they don’t match the exact impedance of my piezoelectric. Designing a buffer/pre-amplifier became necessary to filter the sounds correctly. Giving performers control over volume lets them express their sonic visions.


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