A quick websearch indicates that in some medical circles 'amusia' is
considered roughly equivalent to the popular term 'tone deafness'
But clearly what we normally mean by 'tone deaf' is considerably more
trivial and less debilitating than the real medical condition, and
usually just involves people being self-deprecating because they
haven't developed certain skills.
A person with true amusia would not just be unable to reproduce
musical patterns, but would also find any musical phenomena devoid of
any meaning at all.
I'm sure lots of people with few enough skills who call themselves
'tone deaf' are perfectly capable of being swept away by a piece of
music they really like, and this is something utterly
incomprehensible to one with amusia.
A superficial glance at some of the medical articles that turned up
in the search suggests that this can be an acquired condition,
presumably as a result of some sort of brain injury.
That would be pretty awful, wouldn't it?
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