The measurements in the table allow for the following conclusion: Stiff and dense materials like steel and granite allow sound to propagate extremely fast (5-6 km/s) while lower density ones, like the fluids, reduce this speed to about 1.5km/s, with the lowest-density media (gases) allowing for only order of hundreds of m/s.
The measurements are consistent with a model of energy propagation consisting of spheres (modeling the molecules) and springs connecting them (modeling the molecular bonds). It can be shown that the mass of the spheres and the stiffness of the springs are factors in speed of energy propagation.