Analysis of cello and cellist playing position

This web article is a lay-language adaptation and extract from a master's thesis that took place within the project "Investigating cello sound production beyond ordinary bowing":

Scheiblauer, Anna (2025)
The cello position and the cellists’ bow movement: Analysis of the cello sitting position and bow movement using motion capture

Department of Music Acoustics – Wiener Klangstil, University of Music and Performing Arts Vienna.  

Abstract:

The way cellists sit and hold the instrument is very important for their technique and to prevent injuries. To learn more about the cellist–cello interaction, this study recorded expert cellists using motion-capture cameras to obtain their sitting position and the motion of the bow in 3D. The study also served to find a position at which we could fixate the cello on a playing platform so that it could be played comfortably by human players as well as by a robotic arm. We compared the situation where players could play freely with the situation where the cello was placed on a special stand that kept it from moving while they played. These investigations gathered information about the cello's position, the cellist's sitting habits, and the way the bow is moved. 

Experimental setup and participants:

The recordings took place in a motion capture laboratory using 12 Optitrack Prime 13 infrared cameras arranged in a rectangular shape, operating at 240 frames per second (fps). The cello, the bow, the playing table and some body parts of the cellist are equipped with reflective markers that allow the motion-capture recording. The measurements involved recording movement, sound, and video simultaneously. 

A playing platform was designed to compare normal playing conditions with playing on a fixed instrument. This setup allows both a robotic arm and a human player to bow on the cello. We also look at how the participants are positioned in relation to their instrument. The playing platform and the position of the cello could be adapted to each participant.

Six participants took part in the study. All of them were either current or former students of the mdw (University of Music and Performing Arts Vienna) and had between 12 and 25 years of experience. The participants ranged in height from 157 to 183 cm. They were equally divided between men and women and were between 25 and 30 years old. 

Parameters of the analysis:

To investigate the effect of the playing setup on the player, first the cello and bow movement are visualized and compared for three tested conditions: A) playing freely like in a concert situation, B) playing with the cello fixed at a chosen position by each player, and C) the cello is fastened at the same position for all players. Then some parameters are extracted from the motion-capture recording, as seen in the image: inclination of the cello, length of the cello spike, height of the chair, distance between chair and spike, inclination of the torso, and knee angle. These parameters were then compared with the participant's heights and the sizes of some of their body parts (see [1] for the full study). 

In a following analysis we also obtained playing parameters: the parameters that the players change during bowing, which can be extracted from the motion-capture data: bow-to-bridge distance, the angles between the bow and the strings, the bow velocity... 

Results:

Many interesting results were obtained from the measurements with cello players. The following figure shows an example of how five different players would perform a set of bow changes (changing from bowing up-bow to down-bow) on all four strings of the cello. Although the movement of one single marker attached to the frog of the bow seems very similar among players, once we compute the distance from the bow to the string, we can observe how every player has a different strategy to go closer or further away from the bridge at every string. We can also validate that the angle between the bow and the string is around 90 degrees, as players learn to maintain this angle for proper technique. Finally, we can see how the inclination of the bow on the instrument depends on the played string, and that is how players can select which string is played. 

Conclusion:

Anna Scheiblauer's studies within the project "Investigating cello sound production beyond ordinary bowing" helped to find a position of the cello on the playing platform that would be used throughout the project to record both human players and a robotic player. Some participants had difficulty adapting to an instrument that could not move; most players showed similar bowing patterns in a free and in a constrained setup. They also reported that the setting did not have a negative effect on their playing. Yet we observed that if the cello was fastened, players would adapt their posture (tilt of the torso, knee angle...) so that they would get a comfortable position around the instrument to achieve the same reach with the bow. The study observed that the bow-holding strategy as well as the bow movement on the strings did not change. Therefore, it was concluded that the desired dual setup with a fastened cello is indeed possible; yet enough room has to be left for the player to move freely around the instrument and adapt other parameters, like the seat position and height. During the process, we observed correlations between the length of the spike and the angle of inclination of the cello, while both depend on the height of the cellist. 

References:

Anna Scheiblauer, Alexander Mayer, Montserrat Pàmies-Vilà (2022) 
"Investigating the cello position, bow motion and cellist posture using motion capture",
Proc. Meetings on Acoustics (Vienna Talk 2022), Vienna. 
https://doi.org/10.1121/2.0001677