Amusia is a musical disorder that appears mainly as a defect in processing pitch but also encompasses musical memory and recognition.[1] Two main classifications of amusia exist: acquired amusia, which occurs as a result of brain damage, and congenital amusia, which results from a music-processing anomaly present since birth.
Studies have shown that congenital amusia is a deficit in fine-grained pitch discrimination and that 4% of the population has this disorder.[2] Acquired amusia may take several forms. Patients with brain damage may experience the loss of ability to produce musical sounds while sparing speech,[3] much like aphasics lose speech selectively but can sometimes still sing.[4][5] Other forms of amusia may affect specific sub-processes of music processing. Current research has demonstrated dissociations between rhythm, melody, and emotional processing of music.[6] Amusia may include impairment of any combination of these skill sets.