Vocal cord. So plz explain me in detail!

I want to ask u how the vocal cords vibrate i mean if i speak loudly in mind will my vocal cord vibrate or if i keep my mouth close and then speak in mind loudly but tongue moves little bit then will it vibrate bcz i am on voive rest but i wanted to do affirmation for my health but can't speak so i wanted to do it in mind but continuously speaking same sentence in mind makes toungue to move a little even if mouth is closed so i m afraid that it will vibrate my vocal cord and then my ulcers will become more problematic plz guide me how to talk in mind continuosly without vibrating vocal cords bcz some people said if u talk loudly even in mind and toungue moves then your vocal cords gets vibrates so it will create further prblm for u so plz explain me in detail