Another thing that confused me for a long time and I see confuses lots of people.
The voice is not talking. And talking is not communicating. Talking is part of communicating. The voice is part of talking.
So what is the voice?
The voice is a noise comes from the voicebox. The voicebox sits behind the Adam's apple at the top of the trachea or windpipe. It is made up of two vocal chords which form a "V" shape. They make sound by vibrating when air is forced between them. That air comes from the chest in the form of breath. Usually an outbreath although it is possible, with practise, to make a kind of voice on the inbreath. Air can go through the voice box without engaging the voice box. Normal breathing does not engage make any voice. But neither does whispering. Whispering is "unvoiced" speech. It is done in the mouth.
The voicebox has muscles which make the chords tighter and slacker and that changes the pitch.
Volume is controlled by changing the force of air through the chords. This can be done by pushing more air through them, or by tightening the chords. Doing it by tightening the chords leads to damage so having more air if preferable method: hence the use of the diaphragm and other auxiliary breathing muscles to create volume. This is what is called "supporting" the voice.
The voice does not have to make words, it might also grunt, cough, laugh, growl, sing etc.
So breathing may lead to voice. And voice may or may not lead to words and talking. Which may or may not lead to communicating.
Communication is something else altogether of course. You may may communicate with words but without the voice by whispering. Or you may communicate without words but with voice by grunting. Or you may communicate without voice or words by actions. Or you may communicate nothing at all with voice and words and actions.