The diaphragm during inhalation and exhalation.
The diaphragm is a large, smooth, dome-shaped muscle, attached to the bottom of the lungs, which separates the chest cavity from the abdominal cavity. It plays a crucial role in inhalation – breathing in. Proper use of the diaphragm is vitally important in singing for what is known as breath support.
The diaphragm and inhalation
To start an in-breath, the diaphragm contracts, moves downward into the abdomen, and flattens. This increases the volume and thus decreases the pressure in the chest cavity. The pressure being less now inside the chest than outside the body, air rushes in, via the nose and mouth, to the lungs. During exhalation the diaphragm relaxes and the elasticity of the lung causes air to be pushed back out.
Central to all good singing is correct use of the diaphragm. When breathing in, there should be no rise of the shoulders or swelling of the chest because this leads to shall breaths and a lack of breath support. Instead, the belly button should rise on breathing in, showing that the diaphragm has moved down deeply and caused to be sucked well down into the lungs and making plenty of air available for strong, sustained, and controlled vocalization. There are many effective breathing exercises which encourage proper use of the diaphragm.