When a musician takes a bow to a string instrument, they rely on technique and intuition to produce a desired tone. But what exactly defines the limits of playability and the quality of the sound? What factors influence string vibration, and which of these depend on the player’s technique versus the string itself? These are the central questions driving my doctoral research at the Department of Music Acoustics of the mdw.
To answer them, I used a highly controlled experimental setup with a cello string mounted on a monochord and played by a robotic bowing system. This system could precisely vary bow force, speed, acceleration, and position, allowing for thousands of repetitions under carefully monitored conditions. The main objective here was to map out how the string vibrates depending on the way it is bowed. Through use of this setup, I generated high-resolution versions of two classic visualization tools in bowed-string research: the Schelleng diagram (for steady tone) and the Guettler diagram (for attack). These diagrams illustrate the various ways in which the string can vibrate, including clean, steady Helmholtz motion, double slips, and noisy, unstable behaviours such as raucous motion. The diagrams also show how long it takes for a string to “settle” into a steady vibration after the bow first touches it. This helps us understand how quickly the string responds and how easily it produces a clean, clear sound. I think that my research effects a net contribution to this area, where experimental data are still limited.
I tested and refined theoretical models that define the conditions for achieving so-called “perfect attacks” (those that produce a clean sound right from the first instant of the stroke). Furthermore, I also compared how different string types respond during the attack, identifying measurable differences in playability and responsiveness. Using steady bow strokes, similar to détachés, I performed a detailed analysis of string vibration under a wide range of bowing conditions, including extreme ones. My results confirmed some patterns observed in earlier studies while also revealing new behaviours. I compared the performance of different string types to see which ones were easier to play and produced a richer or brighter sound. While differences between strings were clearly visible in the data, isolating exactly what mechanical properties are responsible for such differences remains a challenge.
Looking ahead, a promising next step will be to use the same robotic setup to imitate real playing gestures more closely. This could help us understand how specific bowing techniques affect sound and why certain gestures feel more “playable” to musicians.
This research was funded in whole or in part by the Austrian Science Fund (FWF) [10.55776/P34852].
References:
A. Lampis, A. Mayer, and V. Chatziioannou, “Assessing playability limits of bowed-string transients using experimental measurements,” Acta Acustica 8, 44 (2024). (https://doi.org/10.1051/aacus/2024034).
A. Lampis, A. Mayer, and V. Chatziioannou, “An experimental approach for comparing the influence of cello string type on bowed attack response,” JASA Express Letters 4, 113201 (2024). (https://doi.org/10.1121/10.0034330).
A. Lampis, A. Mayer, M. Pàmies-Vilà, and V. Chatziioannou, “Examination of the static and dynamic bridge force components of a bowed string,” Proceedings of Meetings on Acoustics 51, 035002 (2023). (https://doi.org/10.1121/2.0001755).
