FIG. 4.

(Color online) Sound amplitude of stationary oscillatory solutions. The dark, bold lines indicate stable oscillatory solutions. Thinner, lighter lines indicate unstable limit cycles. The lines in the (α, ω₀) plane delimit the region of coexistence of fixed points. On these lines, $\frac{\partial g}{\partial \omega }=0$ indicating the occurrence of saddle-node bifurcations of fixed points. The point where they meet is where a cusp bifurcation occurs. Parameters used were the same as in Fig 3.