One of the cornerstones of learning to sing is knowing how to breathe correctly and learn to control your breathing , so that it is used to optimum effect when you sing.
When we are born, our breathing is naturally correct: babies can breathe, yell and scream with optimum effect because they use their lungs without conscious thought. As we grow older, we tend to get lazy and only use the upper part of our lungs, taking shallow breaths as required, rather than a deeper, more natural breath.
To understand how correct breathing and breath control works, first you need to understand the process that breathing involves:
At the bottom of your lungs there is a large (upside down bowl shaped) circular ring of muscle called the diaphragm.It is attached to the lower rib cage and spine. During inhalation the diaphragms contracts and is pulled downwards, gently pressing on the the stomach and intestines.. This increases the space within the lungs and creates a slight vacuum effect inside the chest cavity. Air is gently sucked into the lungs via the nose and mouth
Inside the lungs there are lots of branches (bronchal tubles) which end with the alveoli sacs. Here is where the gaseous exchange takes place: waste carbon dioxide from the body is exchanged for a fresh supply of oxygen by the blood travelling across the very thin membranes of the alveoli sacs.
Exhalation (breathing out)
Within a few seconds, the diaphragm muscles relaxes and the diaphragm slowly moves back to its original position, decreasing the space within your chest cavity and essentially pushing the (waste) air out of your lungs.
Breathing is essentially an autonomic reflex, controlled by your brain, in that your body does it without you having to think about it. How fast you breathe depends on your oxygen requirements. However, you do have some control over your breathing, enabling you to hold your breath, speak a sentence, or sing a song.