If you want to hum the piece quietly to yourself, that's fine; that's good.

如果你想自己跟着曲子,小声哼哼,没问题,那很好

耶鲁公开课 - 聆听音乐课程节选

You should yell it out, not just whisper it.

应该大声说起来，而不是小声地在下面说。

麻省理工公开课 - 热力学与动力学课程节选

I heard it somewhere very quietly.

我听到有人在非常小声的说。

麻省理工公开课 - 计算机科学及编程导论课程节选

So I ask you to keep that to a minimum.

所以请你们尽量小声说话

耶鲁公开课 - 基础物理课程节选

If I hear lots of buzzing out there, that means you're into it, so hum the piece a little bit to yourself, Musorgsky's "Great Gate of Kiev" Here and Pictures at an Exhibition and see if you can write down those particular symbols.

如果我听到了很多嗡嗡声,就说明你们都投入进去了,那就自己跟着曲子小声哼哼吧,穆索尔斯基的《基辅的城门》,以及《图画展览会》,看看你是否可以写下那些特殊符号来

耶鲁公开课 - 聆听音乐课程节选