(a) Evolution of the residual associated with the least squares solution of equation (7) throughout the iterative reconstruction of the input impedance shown in Figure 1. Each iteration corresponds to the execution of one action by the user, among the four possible ones. Each action is labeled by a letter (see the text for the description of each action). (b) Evolution of poles, represented by their natural frequencies f_n and damping ratios ξ_n, throughout the iterative approximation of the input impedance. The color indicates the progression of this process, using the same colormap as in (a). The locations of poles at iteration 23, corresponding to the result shown in Figure 1, are highlighted (blue circles). Vertical dotted lines indicate a harmonic series based on the second resonance frequency.