The chief cause of breath exhaustion is wasted breath. This waste comes from exhaling more breath (more motive power) than the tone requires, and breath that does not become tone is wasted. This fault is largely induced by lack of proper resonance adjustment.
The singer should always feel able to sing another note or to speak another word. To sing or speak thirty or forty counts with one breath is useful practice but poor performance. Occasionally, long runs in singing may compel an exception. Half-empty lungs lower the pitch of the tone, lessen the resonance, and weaken the voice, rendering the last note of the song and the last word of the sentence inaudible. The breathing must not be forced, but enough air must be furnished to produce the proper full vibrations.
BREATH MASTERY
What then does perfect control of the breath mean?
1. Ability to fill the lungs to their capacity either quickly or slowly.
2. Ability to breathe out as quickly or slowly as the occasion demands.
3. Ability to suspend inspiration, with the throat open, whether the lungs are full or not, and to resume the process at will without having lost any of the already inspired air.
4. Ability to exhale under the same restrictions.
The above four points are common to speaking and singing, but singing involves further:
5. Ability to sing and sustain the voice on an ordinary breath.