One of them is the technique you saw me do with my left hand where I wiggled it a little bit. It's called vibrato.

其中有个技巧,你们看我左手的手法,我略微揉动琴弦引发出颤音

耶鲁公开课 - 聆听音乐课程节选

You can do it on other instruments but on a string instrument it's the difference.

很多乐器都能奏出颤音,但弦乐器上　这种揉弦产生的颤音是不一样的

耶鲁公开课 - 聆听音乐课程节选

You hear it in human voices as well.

人类的嗓音也有这种颤音

耶鲁公开课 - 聆听音乐课程节选