Mechanics of character's mouth opening when a person speaks into a microphone

Greetings everyone, I am currently looking to develop a cooperative horror game along the lines of R.E.P.O, and others. In these games, a microphone mechanic is developed so that when a person speaks, the character’s mouth moves.
On the Internet I found a video that tells how to bind the microphone to the game, so that you can talk and the game caught the voice, but it is the mechanics of opening the mouth of the character I did not find.
I would be grateful if someone could explain to me how to do it, or find on the Internet how to do it.

P.S. I am a novice developer, if someone decides to help me, I will ask to do it in simple language, thank you!

Thank you very much in advance for the answer (if any). I will understand any answer, even if it is negative! Thank you!