An ongoing research theme is identifying and exploiting similarities in exotic behaviors of light and sound waves. The titular device is the acoustic analogue of a metal-insulator-metal plasmonic waveguide. This study experimentally analyzes and validates the properties of the proposed waveguide, in terms of its dispersion and modal properties. Similar to a plasmonic waveguide, the proposed acoustic waveguide, and its supported symmetric and antisymmetric modes and group and phase velocities, can be largely controlled by changes in geometrical parameters, opening the possibility of applying this technology in acoustic tunable delay lines, modulators, and sensors.