See the Pen MVgRZx by Héctor (@hector39) on CodePen.
We create the variable mic, then we call the microphone and tell it to activate, after we tell it to give us the sound value that the microphone detects, with that value that gives us the map and we put a name to that varibale, and for last we put the variable where we want to put it so that the value that we have mapped makes a change each time the sound is bigger or smaller.