This is the most important chapter in this book.
This, you might think, seems a bit strange, since this book is about screen acting, and you would expect the main thrust to be about the look of things rather than the sound of them.
I put this as the most important because, in my experience, the main reason why good actors are not good on screen is that they have their vocal levels wrong. Time and time again, I see a good performance (or a good potential actor) ruined by speaking too loudly, and the performance coming across as "too theatrical." In that twenty second acting exercise that you did in chapter 4, you also got the sound level wrong, didn't you? You broadcast your performance loudly to the whole group, rather than to the microphone. Why do you think during the exercise I kept moving the microphone? It was reminding you of what it was doing, and how close it was.
Again, we need to go back to the basics.
In real life we vary our level of speaking according to how excited or passionate we may be, and how far away the person is that we are speaking to.
On stage, we do the same, but also incorporate how far away the furthest member of the audience is.
And on screen? Here, although the person we are speaking to may be on the other side of the room, the effective distance we should project to varies according to the size of shot.