(a) Measured fundamental frequency (blue markers) of self-oscillations as functions of the applied fingering, for a feedback gain Γ₀ ≈ 1.5, and for L_cav = 3 cm. The calculated fundamental frequencies of self-oscillations are also reported with green markers. (b) The corresponding experimental (blue lines) and simulated (green lines) acoustic pressure sensed by the feedback microphone (u/S_μ) or the one radiated 20 cm away from the open end of the duct p_rad, are also plotted for different fingerings, namely from all side holes closed on top, to all side holes open on the bottom.