A Simple, Quasi-linear, Discrete Model of Vocal Fold Dynamics

In current speech technology, linear prediction dominates. The linear vocal tract model is well justified biomechanically, and linear prediction is a simple and well understood signal processing task. However, it has been established that, in voiced sounds, the vocal folds exhibit a high degree of nonlinearity. Hence there exists the need for an approach to modelling the behaviour of the vocal folds. This paper presents a simple, nonlinear, biophysical vocal fold model. A complementary discrete model is derived that reflects accurately the energy dynamics in the continuous model. This model can be implemented easily on standard digital signal processing hardware, and it is formulated in such a way that a simple form of nonlinear prediction can be carried out on vocal fold signals. This model could be of utility in many speech technological applications where low computational complexity synthesis and analysis of vocal fold dynamics is required.