While various causes of amusia exist, some general findings that provide insight to the brain mechanisms involved in music processing are discussed below. Pitch relations
Studies suggest that the analysis of pitch is primarily controlled by the right temporal region of the brain. The right secondary auditory cortex processes pitch change and manipulation of fine tunes; specifically, this region distinguishes the multiple pitches that characterize melodic tunes as contour (pitch direction) and interval (frequency ratio between successive notes) information. The right superior temporal gyrus recruits and evaluates contour information, while both right and left temporal regions recruit and evaluate interval information. In addition, the right anterolateral part of Heschls gyrus (primary auditory cortex) is also concerned with processing pitch information. Temporal relations
The brain analyzes the temporal (rhythmic) components of music in two ways: (1) it segments the ongoing sequences of music into temporal events based on duration, and (2) it groups those temporal events to understand the underlying beat to music. Studies on rhythmic discrimination reveal that the right temporal auditory cortex is responsible for temporal segmenting, and the left temporal auditory cortex is responsible for temporal grouping. Other studies suggest the participation of motor cortical areas in rhythm perception and production. Therefore, a lack of involvement and networking between bilateral temporal cortices and neural motor centers may contribute to both congenital and acquired amusia. Memory
Memory is required in order to process and integrate both melodic and rhythmic aspects of music.
While a method of treatment for people with amusia has not been defined, tone differentiation techniques have been used on amusic patients with some success. It was found with this research that children reacted positively to these tone differentiation techniques, while adults found the training annoying. However, further research in this direction would aid in determining if this would be a viable treatment option for people with amusia. Additional research can also serve to indicate which processing component in the brain is essential for normal music development. Also, it would be extremely beneficial to investigate musical learning in relation to amusia since this could provide valuable insights into other forms of learning disabilities such as dysphasia and dyslexia. Notable cases
In fiction
Horatio Hornblower
Grace from Home on the Range
James Fraser from Outlander by Diana Gabaldon
Rodrigo from Mozart in the Jungle

See also
Absolute pitch, the human ability to name a musical note when played or sung (less common than relative pitch)
Auditory agnosia
Cognitive neuroscience of music
Color blindness
Musical aptitude
Music-specific disorders
Relative pitch, the human ability to accurately distinguish pitch intervals (more common than absolute pitch)
Synesthesia
Tonal memory

References
Further reading
Kazez D (1985). "The myth of tone deafness". Music Educators Journal. 71 (8): 46–47. doi:10.2307/3396499. JSTOR 3396499. S2CID 144988256. Kleist, Karl (1962). Sensory aphasia and amusia; the myeloarchitectonic basis. Oxford: Pergamon Press. OCLC 1649635. External links
MedicineNet: Amusia
NIH: Distorted Tunes Test
The Listening Book: Tone-Deaf Choir audio description by W. A. Mathieu