<P> Music agnosia, an auditory agnosia, is a syndrome of selective impairment in music recognition . Three cases of music agnosia are examined by Dalla Bella and Peretz (1999); C.N., G.L., and I.R. . All three of these patients suffered bilateral damage to the auditory cortex which resulted in musical difficulties while speech understanding remained intact . Their impairment is specific to the recognition of once familiar melodies . They are spared in recognizing environmental sounds and in recognizing lyrics . Peretz (1996) has studied C.N.'s music agnosia further and reports an initial impairment of pitch processing and spared temporal processing . C.N. later recovered in pitch processing abilities but remained impaired in tune recognition and familiarity judgments . </P> <P> Musical agnosias may be categorized based on the process which is impaired in the individual . Apperceptive music agnosia involves an impairment at the level of perceptual analysis involving an inability to encode musical information correctly . Associative music agnosia reflects an impaired representational system which disrupts music recognition . Many of the cases of music agnosia have resulted from surgery involving the middle cerebral artery . Patient studies have surmounted a large amount of evidence demonstrating that the left side of the brain is more suitable for holding long - term memory representations of music and that the right side is important for controlling access to these representations . Associative music agnosias tend to be produced by damage to the left hemisphere, while apperceptive music agnosia reflects damage to the right hemisphere . </P> <P> Congenital amusia, otherwise known as tone deafness, is a term for lifelong musical problems which are not attributable to mental retardation, lack of exposure to music or deafness, or brain damage after birth . Amusic brains have been found in fMRI studies to have less white matter and thicker cortex than controls in the right inferior frontal cortex . These differences suggest abnormal neuronal development in the auditory cortex and inferior frontal gyrus, two areas which are important in musical - pitch processing . </P> <P> Studies on those with amusia suggest different processes are involved in speech tonality and musical tonality . Congenital amusics lack the ability to distinguish between pitches and so are for example unmoved by dissonance and playing the wrong key on a piano . They also cannot be taught to remember a melody or to recite a song; however, they are still capable of hearing the intonation of speech, for example, distinguishing between "You speak French" and "You speak French?" when spoken . </P>

What part of the brain is responsible for music