Your voice is controlled by the amount of air that you take into your lungs.
1volume
2tone
3vocal pitch

The volume is controlled by the amount of air

an expression designed to call something to mind without mentioning it explicitly; an indirect or passing reference.

it is the background information on the characters and setting explained at the beginning of the story. the exposition will often have information about events that happened before the story began. the exposition is often the very first part of the plot.