The bass is going where the upper voice has .

低音出现在原来高音的位置上

耶鲁公开课 - 聆听音乐课程节选

So we'll focus on the bass and we'll try to sing the bass, and if we find that in singing the bass our voice is not changing, probably the harmony hasn't changed.

现在把我们的注意力放到低声部上，尽量唱出低声部，如果在唱的过程中我们觉得自己的声音没有变化，那和声就很有可能没有改变。

耶鲁公开课 - 聆听音乐课程节选