Playbacks are important.

回馈是重要的。

About two hours and 3,000 playbacks later, the students were able to correctly identify 80 % of the heart sounds on a test—up from 30 % before the practice listening session.

在两个小时中，他们反复听了3000遍，之后他们就可以在测试中准确地分辨出80％的心脏跳动声，相比听力练习前提高了30％。