Can interference take place in medium itself?

"Interference" is misunderstood. Interference never causes energy loss, energy is always stored in the medium at "dark" or zero amplitude locations. This is true for sound, water and even EM waves. Energy is only taken out of the medium by absorption ... like waves crashing on the beach or photons being absorbed by an atom or molecule. The classical interpretation of the DSE says dark bands are where photons are cancelled which is a gross over simplification and this is what is widely taught until you take quantum optics.

An important property of photons is they must travel an integer number of wavelengths, in the DSE there is no energy (no photons) in the dark areas, all the photons take the path to the bright areas. The photons take the most probable (quantum mechanics) path where they can transfer their energy to an atom.

In the DSE photons take a probable path to the screen but final absorption occurs in you eye! .... of course many photons just get absorbed by the walls/apparatus.

For a beam (propagating light) we know thanks to Maxwell that an E field vector and an M field vector have a sinusoidal shape in time and distance. What is interesting is that even for a single photon the EM fields grow and shrink together from a max amplitude to zero! and this propagation repeats itself over and over until absorption. I believe it is considered a property of the EM field that it effectively contains the energy of the photon even though its E and M are zero at many points in the propagation.

Similarly if 2 photons or 2 beams are "interfering" in the EM field the EM field holds or conserves the energy. An analogy is if 2 water waves are passing into each other, for a brief second the surface of the water is completely calm ..... but a second later the waves reemerge ... the energy was stored in the elasticity/compressibility of the water.