How do you spell the sound of phlegm?

There isn't one specific spelling for the sound of phlegm. It depends on the context and the dialect. Here are some possibilities:

* "flem": This is the most common spelling, and it's often used in informal contexts.

* "flegm": This is the more formal spelling, which is often used in medical contexts.

* "flem" or "flem": Some people pronounce it with a more guttural sound, and these spellings reflect that.

Ultimately, the best way to know how to spell the sound of phlegm is to listen to how the person you are talking to pronounces it.