Hearing sounds, particularly voices, which have no source or explanation in the physical world. Can be due to certain mental illnesses, such as schizophrenia, hearing loss, or neurological problems such as epilepsy.
Example: The patient hears a voice coming from the heating vent, even though he is the only one in the room. It threatens and derogates the patient, and tells him to kill himself.
Grinnell, R. (2011). Auditory Hallucination. Psych Central. Retrieved on August 3, 2015, from http://psychcentral.com/encyclopedia/2008/auditory-hallucination/