Thanks for the book about how to deepen your voice.  I think that it is really really good, I think is the thing that I was looking for, With respect to the first deeper voice exercice I’m having a hard time trying to understand  what you mean when you said:

1- On your bed, lay vertically on your back with your head and shoulders hanging off the edge.

2 – Tilt your head back and forth, up and down, tensing your neck muscles with each movement.

3 – Hold your head in each position for 10 seconds, and slowly release your head back to its original position.

I don’t know if I have to sit down on the bed, or lay down on the bed, can you please explain in other words, do you have a picture of this exercice.