We present numerical simulations and experimental measurements for ultrasonic transmission through a subwavelength metamaterial consisting of an array of hollow cylinders embedded in a soft elastic matrix. The mechanical properties of the matrix, the lattice constant, and the size of the cylinders are optimized in order to maximize sound absorption in the metamaterial while the cylinders are filled with air. The acoustic transmission is restored when the cylinders are filled with water. Our design expands the concept of metamaterial as it demonstrates the ability to tune the acoustic properties of a subwavelength material.