CONGENITAL AMUSIA, OR 'TONE DEAFNESS,' IS A LIFELONG impairment in musical ability, reported to be present in approximately 4% of the general population.We examined the meaningfulness of 4% as an estimate of the prevalence of amusia given current test-based methods; here we focused on the Distorted Tunes Test (DTT) and the Montreal Battery of Evaluation of Amusia (MBEA). We demonstrate that estimates of prevalence critically depend on the specific cutoff applied to the test and the degree of skew in the distribution of scores. Broader consideration of this issue reveals that the use of arbitrary cutoffs is not unique to diagnosis of congenital amusia. We conclude that although the MBEA has shown to be a valuable diagnostic tool, caution is warranted against attributing meaning to the reported 4% rate of congenital amusia that is so widely cited in the literature.
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