This is an interesting article, but I am confused as to how anything is nonlinear. The motion of the Helmholtz corner looks like it could be the solution to a linear wave equation. Also isn't the sticking and slipping analogous to just repeated plucking of the string in exact sync with the motion of the wave packet down the string? Lastly, I was under the impression that the spectrum of a violin is a harmonic series, which I thought typically indicated that a system was behaving linearly. So I guess my question is: Is this motion the solution to a dampened linear wave equation with a forcing term or not? Also how does chaos come into this? Is there a turbulence before the system becomes chaotic? What does the chaotic state sound like? Is thre a well defined pitch during the chaotic state or is it just white noise?