Insights into the string-barrier interaction dynamics based on high-speed camera measurements

Analysis of nonlinear phenomena associated with string– barrier collision dynamics is a long-standing open problem in musical acoustics. In order to advance towards a complete understanding of the problem good supporting experimental data are needed. The experimental and theoretical analysis of the string vibration in the monochord equipped with a smooth and rigid barrier is presented. The experimental data are gathered using video-kymographic technique that relies on digital image analysis of high-speed line-scan camera imagery. The data are then compared against a time-stepping model proposed by the authors. The measurements show that the string–barrier dynamics features two distinct vibration regimes. The initial shortlasting violent regime characterised by the high energy collisions and the resulting pitch glide effect, and the more peaceful regime characterised by the nonlinear inter-modal energy transfer phenomenon. It is shown that the proposed model can predict many aspects of the investigated system. The results and methods presented here should in general find application in string instrument acoustics of similar phenomena.