it's similar to being a vocalist, except instead of it coming out of your throat, you're controlling it just in the air and you don't really have a point of reference; you're always relying on your ears and adjusting constantly.
这和做歌手有点像，除了， 声音不是从你的喉咙里发出的， 而是你用手在空中控制它 而且你没参考点； 你总得靠自己的耳朵听，不断调整。