Tune Deafness

Description

Tune deafness, or congenital amusia, is a lifelong deficient in music perception that cannot be explained by hearing loss, brain damage, intellectual deficiencies, or lack of exposure. The disorder affects predominantly the melodic pitch dimension (summary by Peretz et al., 2009).

See 159300 for an opposite situation, that of musical perfect pitch.

Clinical Features

Peretz et al. (2002) reported a middle-aged woman with congenital amusia, an impairment of the ability to discriminate, recognize, and appreciate melody since birth. She had no cognitive deficits, brain lesions, hearing loss, or socioaffective disturbances, and was exposed to music as a child. She did not like to listen to music because it sounded to her like noise and induced stress. Detailed tests showed an inability to discriminate pitch variation, and to a lesser extent temporal variation, while retaining the ability to recognize speech intonation and voices. Other family members were reported to be similarly impaired, although they were not formally tested. Peretz et al. (2002) concluded that fine-grained pitch perception is an essential component around which the musical system develops in a normal brain.

Inheritance

Seashore (1940) reviewed the complexity of the problem of the inheritance of musical ability.

Kalmus (1949) studied tune deafness in a group of Continental and British students at University College in London. He found a bimodal distribution in population investigations, with frequent segregation in families and sib pairs. He suggested this might be caused by a unit gene substitution, possibly a dominant. Kalmus and Fry (1980) used the distorted tunes test in family studies. Segregation suggesting 'an autosomal dominant trait with imperfect penetrance' was found.

Drayna et al. (2001) used a twin study to investigate the genetic and environmental contributions to differences in musical pitch perception abilities in humans. They administered a Distorted Tunes Test (DTT) to 136 monozygotic twin pairs and 148 dizygotic twin pairs. The correlation of DTT scores between twins was estimated at 0.67 for monozygotic pairs and 0.44 for dizygotic pairs. Genetic model-fitting techniques supported an additive genetic model, with heritability estimated at 0.71 to 0.80, depending on how subjects were categorized, and with no effect of shared environment. DTT scores were only weakly correlated with measures of peripheral hearing. This suggested that variation in musical pitch recognition is primarily due to highly heritable differences in auditory functions not tested by conventional audiologic methods.

To estimate whether congenital amusia can be genetically transmitted, Peretz et al. (2007) performed direct auditory testing of 13 amusic probands and 17 controls, as well as 58 members of 9 large families of the amusic probands and 58 members of 10 of the control families. The results confirmed that congenital amusia is expressed by a deficit in processing musical pitch but not musical time, and that the pitch disorder has a hereditary component. In the amusic families, 39% of first-degree relatives had the same disorder, whereas only 3% had it in the control families. The authors noted that offspring in both sets of families had considerably more musical experience than their parents and that the relative risk of offspring compared with their parents was low (2.3), suggesting that congenital amusia can be less penetrant when the musical environment is enriched.

Population Genetics

Kalmus and Fry (1980) estimated that the frequency of tune deafness in the British population is 4.2%.