Musical hallucinations associated with acquired deafness.

Two patients with auditory hallucinations beginning after a long history of progressive bilateral hearing loss were studied. The hallucinations included both unformed (tinnitus and irregular sounds of varying pitch and timbre) and formed (instrumental music, singing and voices) components, and were repetitive. They were affected by ambient noise levels; their content and speed were influenced by attentional and intentional factors. There was no evidence of global dementia, nor of epileptogenic or psychiatric disturbance. A combination of peripheral and associated central "disinhibition" may be responsible for the occurrence of such hallucinations.