You will notice that all of our teachers have very clear audio; this is because they have an external microphone rather than use the microphone that is built in to their computer. When you do the audio/video test, what you see and hear is exactly how your teacher will see and hear you. If your audio isn’t very clear, 95% of the time this is because your voice is being recorded by a microphone built into your computer, and usually this microphone is of very low quality even on expensive computers.
There are a few good options for getting a better microphone:
A standalone microphone is a great option, and can be had for less than $10 USD. Search Amazon for a term like “desktop microphone”.
Almost all webcams come with a microphone. Most of these are of good quality.
Headsets are a great option if you don’t mind wearing one. In our experience, Logitech is one of the better brands but there are many good options.