Amusia is a kind of aphasia .

失歌症是失语症的一种。

About 4 % of the population has " amusia " of one sort or another , and at least some types of amusia are known to be heritable .

约4%人口患有各种程度的“失歌症”，并且我们已经知道至少某些失歌症具有遗传性。