centered at each linear defect. We can observe the intensity of the sound waves of frequency $1.9\times 10^5\,\rm{Hz}$ propagating along the designed structure for three different values of the phase difference $\varphi$ between the input sources: (a) $0$, (b) $\pi/2$ and (c) $\pi$. We can clearly see that the intensity at the output depends on the phase difference and that for $\varphi=0$ ($\varphi=\pi$) only the S (A) supermode is excited and followed, while for $\varphi=\pi/2$ both supermodes are equally excited and followed. [Fig. \[sc\_figfase2\]]{}(a) shows the dependence of the output intensity in each waveguide on the phase difference, which follows the expected behavior ([Eq. [(\[sc\_Ip\])]{}]{} and [Eq. [(\[sc\_Im\])]{}]{}). Thus, it is possible to obtain the measured phase difference using [Eq. [(\[sc\_def\])]{}]{} as a function of the known phase difference introduced between the sources ([Fig. \[sc\_figfase2\]]{}(b)). The results from the numerical simulations are in good agreement with the analytical ones. Small discrepancies arise only close to $0$ and $\pi$ phase differences. This is due to the impossibility to completely decouple the two linear defects at the input and the output of the system. Nevertheless, a proper calibration of the device would allow for the assignment of a real value of the 