From The Spirit Artist - Rev. Rita Berkowitz:
Mediums do not always recognize when they are awakening the facility of hearing. They are expecting to hear an audible loud voice. Sometimes this will happen; occasionally it will be musical and other times it will be impressions. A name or a word will keep coming to mind or music that is symbolic of a particular occasion such as The Wedding March. As the medium becomes increasingly sensitive there will be a distinct feeling coming into consciousness. Mediums will be able to develop discernment between memories and spirit messages.
Mediums should learn to explore this gift more fully. If you receive a name such as Fred, ask which Fred. Begin a dialogue with the communicator. Find out as much information as you can to prove the identity of the spirit. Mediums should be aware of their posture when clairaudience is flowing and try to repeat this posture to alleviate difficulty.