Also known as paracousis. Both terms stem from the Greek words para (beside, near, resembling, accessory to, beyond, apart from, abnormal) and akouein (to hear). They translate loosely as disordered hearing. The term paracusis is used in a broad sense to denote any kind of false acoustic perception. In a more restricted sense, it refers to a group of disturbances in the perception of isolated notes. Paracusis in the broad sense is commonly divided into three types, i.e. paracu-sis loci (a disturbance of spatial hearing, entailing the false localization of acoustic sources), * paracusis of Willis (also known as paradoxical deafness), and paracusis duplicata (characterized by an audible echo, as sometimes experienced in Ménière's disease). Paracusis in the restricted sense is divided into four subclasses, which partly overlap with the category paracusis duplicata. These subclasses are diplacusis binau-ralis echotica (in which sounds are heard twice, due to the time that may lapse between hearing with a healthy ear and with a diseased ear), dipla-cusis monauralis echotica (in which sounds are echoed within the diseased ear), diplacusis bin-auralis disharmonica (in which a dissonant double clang is produced, due to the disordered processing of sounds by a diseased ear), and diplacu-sis qualitatis (in which the diseased ear changes the quality of notes, without altering their pitch).
References
Ninio, J. (2001). The science ofillusions.Trans-lated by Philip, F. Ithaca, NY: Cornell University Press.
Révész, G. (2001). Introduction to the psychology ofmusic. Translated by de Courcy, G.I.C. Mineola, NY: Dover Publications.
Dictionary of Hallucinations. J.D. Blom. 2010.