In order to probe the process of energy propagation through dense granular systems, we carry out discrete element simulations of the system response to excitations where we control the driving frequency and wavelength independently. The soft-disk simulations are carried out in two spatial dimensions, and include the effects of energy loss due to inelasticity of collisions, frictional damping, rotations, and polydispersity. Our ability to control independently spatial and temporal properties of the imposed perturbations allows us to extract significant new information. In particular, Fourier analysis of the system response shows that properties of the propagating signal strongly depend on the spatial scales introduced by the perturbation itself. Then, we consider a sheared granular system and discuss how shearing influences the nature of the propagating signal. The simulations are carried out using realistic system sizes and material properties, allowing for direct experimental verification of the obtained results.