Fig. 3: Experimental demonstration of phononic topological metal.

a Photograph of the fully assembled acoustic metallized SSH lattice consisting of block resonators and coupling bridges. b Photograph of the inner structure, with all coupling bridges visible. The 3D-printed resonators are open at the bottom and are coupled through the 3D-printed bridges and grooves in the black base when assembled. The acoustic resonators are embedded in the transparent acrylic plate (top) that sits above the black base (bottom). The red dotted squares indicate how the acoustic resonator dimers are mounted on the black base. c Schematic of the phononic metallized SSH lattice showing the domain wall. The SSH layer is terminated in the same manner as Fig. 2. d Full-wave eigenfrequencies of the metallized SSH system consist of 41 dimers. e Measured local density of states, assembled from microphone readings on the 41 dimers of the metallized SSH system. The observed pressure amplitude ∣p∣ is shown in normalized units. LDOS is resolved by the dimer index. The data from the SSH resonator and the data from the metal resonator with the same dimer index are summed together. f Measured acoustic pressure field distribution at 4560 Hz for the domain boundary- and edge-localized modes. g Simulated acoustic eigenpressure fields of the four domain boundary- and edge-localized states. The colored dots in this panel correspond to those marked in c. The color indicates the absolute acoustic pressure ∣p∣, which is displayed in normalized units.