Modeling of tension modulation nonlinearity in plucked strings

In this paper, a nonlinear discrete-time model that simulates a vibrating s tring exhibiting tension modulation nonlinearity is developed. The tension modulation phenomenon is caused by string elongation during transversal vib ration. Fundamental frequency variation and coupling of harmonic modes are among the perceptually most important effects of this nonlinearity. The pro posed model extends the linear bidirectional digital waveguide model of a s tring. It is also formulated as a computationally more efficient single-del ay-loop structure, A method of reducing the computational load of the strin g elongation approximation is described, and a technique of obtaining the t ension modulation parameter from recorded plucked string instrument tones i s presented. The performance of the model is demonstrated with analysis/syn thesis experiments and with examples of synthetic tones available at http:/ /www.acoustics.hut.fi/similar to ttolonen/tmstr_SAP/.