...Researchers caution against labeling people as “tone-deaf” or telling them they “can’t sing.” Only a small percentage of people, about one in 20, suffer from true tone-deafness, a condition called amusia. Past studies have found that most bad singers can discern musical notes perfectly well, and they have similar vocal ranges as good singers.
What they lack, however, is training: People feel so discouraged by being told they’re poor singers that they rarely try to sing—and they never get better.
