Have you ever heard something that you could not readily identify? A noise like a pop or buzzing or very distant chatter? What about a song.. either familiar or not? There are many ways that the Spirits can connect to let you hear a sound. They may want to bring in another Spirit or set a frequency. Perhaps they are bringing you into a new level of consciousness. If it seems like it’s not caused by something in the physical maybe it’s etheric wow. If it’s clairaudience, it will still be audible as if it’s in your physical space without an apparent physical cause. Telepathy is more an impression.. you just know you are receiving sound waves like a tune in your head. Makes you think doesn’t it?