Physics-based synthesis of tanpura drones requires accurate simulation of stiff, lossy string vibrations while incorporating sustained contact with the bridge and a cotton thread. Several challenges arise from this when seeking efficient and stable algorithms for real-time sound synthesis. The approach proposed here to address these combines modal expansion of the string dynamics with strategic simplifications regarding the string-bridge and stringthread contact, resulting in an efficient and provably stable timestepping scheme with exact modal parameters. Attention is given also to the physical characterisation of the system, including string damping behaviour, body radiation characteristics, and determination of appropriate contact parameters. Simulation results are presented exemplifying the key features of the model.

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The virtual exploration of the domain of mechano-acoustically produced sound and music is a long-held aspiration of physical modelling. A physics-based algorithm developed for this purpose combined with an interface can be referred to as a virtual-acoustic instrument; its design, formulation, implementation, and control are subject to a mix of technical and aesthetic criteria, including sonic complexity, versatility, modal accuracy, and computational efficiency. This paper reports on the development of one such system, based on simulating the vibrations of a string and a plate coupled via a (nonlinear) bridge element. Attention is given to formulating and implementing the numerical algorithm such that any of its parameters can be adjusted in real-time, thus facilitating musician-friendly exploration of the parameter space and offering novel possibilities regarding gestural control. Simulation results are presented exemplifying the sonic potential of the string-bridgeplate model (including bridge rattling and buzzing), and details regarding efficiency, real-time implementation and control interface development are discussed.

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