In forcible expiration about one hundred cubic inches may be expelled, but even then the residual air that cannot be expelled is about one hundred cubic inches.
[Footnote 3: Dr.Wesley Mills, _Voice Production_, 1906.] It is not, however, the quantity of breath inhaled that is significant, it is the amount _controlled_.

Get, therefore, all the breath necessary, and keep it, but without undue effort and _without rigidity_.
To test the amount of breath used in prolonged vocalization, a person skilled in the art of breathing, after an ordinary inspiration, closed his lips, stopped his nostrils, and began to vocalize.

He found that the mouth with distended cheeks held sufficient breath to continue a substantial tone for twenty-three seconds.
While these experiments show that very little amount or force of breath is needed to produce effective tones, the impression must exist in the mind of the performer that there is a free flow of breath through the larynx; otherwise the tone will seem restricted and will be weak.

The forced holding back of the breath begets a restraint that has a bad effect on the singer's delivery.

While the breath must be controlled, there is such a thing as an exaggerated "breath control" that makes free delivery of the voice impossible.
It is quite possible to _overcrowd_ the lungs with air.