Measuring Bow Force in Bowed String Performance: Theory and Implementation of a Bow Force Sensor

Abstract

As ensor has been developed which allows measurement of the force exerted by the bowo nt he string (bow force)d uring violin performance. The bowf orce is deduced from measurement of the transversal force at the termination of the bowh air at the frog. The principle is illustrated with an experiment that demonstrates how the bending of the stick and variations in bowhair tension influence the measurements. The design of the sensor is described and performance characteristics are discussed. At horough calibration procedure is described and tested. Finally,the use of the sensor is demonstrated through measurements in real playing situations. PACS no. 43.75.-z, 43.75.Yy 2. Introductory experiment and theoretical considerations The basic idea of the force sensor wast od etermine bow force indirectly by measuring the resulting transversal forces at the bowh air terminations. In this section, the 718 ©S.Hirzel Verlag · EAA Demoucron et al.:B ow pressure measurement ACTA ACUSTICA UNITED WITH ACUSTICA Vol. 95 (2009) ACTA ACUSTICA UNITED WITH ACUSTICA Vol. 95 (2009)

The Augmented String Quartet: Experiments and Gesture Following

“…Unlike the previous cited works that are aimed at artistic performances, these studies are directed towards the understanding of acoustics and/or instrumental performances. These studies typically require accurate capture systems that are generally not compatible with concert settings (Nelson, 1983;Winold, Thelen, & Ulrich, 1994;Wiesendanger, Baader, & Kazennikov, 2006;Schoonderwaldt & Demoucron, 2008;Demoucron, Askenfelt, & Causse´, 2009;Rasamimanana & Bevilacqua, 2009). Instrumental gesture measurements are also carried out for the improvement of sound synthesis based on physical modelling (Demoucron, 2008;Maestre, Blaauw, Bonada, Guaus, & Perez, 2010).…”

Static model of a violin bow: Influence of camber and hair tension on mechanical behavior

“…In most studies, the hair tension has been assumed not to vary significantly from the initial value fixed by the player before playing. However, it has been experimentally shown by Demoucron et al 27 that the hair tension does vary when the bow is loaded by a normal force. The tension variation was found to be almost linear with respect to relative abscissa γ and normal force F y , leading to a simple empirical relation,…”

“…The optimal playing tension was found at 6 turns (T 0 = 54.9 N). Although a typical value of 60 N is commonly refered to as "normal" playing tension by authors 14,26,27 , the optimal value for each bow probably depends on the stiffness of the stick and camber as well. Figure 5(d) shows the nonlinear increase in minimum hair-stick distance with hair tension.…”

Statistical Modeling of Bowing Control Applied to Violin Sound Synthesis

“…Bow velocity profiles are reconstructed by using video data in a postprocessing step [8]. Accuracy and robustness in bow force measurement were recently taken to a higher level (see [9], [10] and a re-implementation in [11]) by using strain gages attached to the frog end of the hair ribbon, thus measuring ribbon deflection. In a more recent approach presented in [12], bowing parameters were very accurately measured by means of a commercially available electromagnetic field-based tracking device.…”

“…Sample transformation is performed in the spectral domain to stored pickup audio signals (e.g., note samples), thus avoiding potential problems introduced by body resonances. Assuming the body filtering effect to be linear, the resulting audio signal is convolved with a body impulse response that was previously obtained by deconvolution as briefly described in Section II-C. Sound synthesis examples are available online 10 . 1) Sample Retrieval: As a first step, a sample candidate list is generated for each th note in the input score by making use of different sample annotations: matching articulation, bow direction, played string, bow context, and silence context (see Section III-A).…”