To enhance voice intensity, you should inhale as little air as possible, opening your larynx as widely as possible.
In order to feel your larynx is widely open, perform your vocal exercises with your lower jaw down and relaxed, your index finger on your chin and the tip of your tongue pressed against your lower fore-teeth.
If you have a nose clip, perform your high pitch exercises with the nose clip on your nose.
It is recommended to perform high-pitch exercises in a “wide-open throat” mode, as part of vocal warming up routine.
Faithfully keeping your voice intact