Share your personal experience.
You can observe the structure of the whistle, which is a space where the cross-section is a box, and finally there is a place to lift, and the air flow is lifted up to vibrate and sound.
You can use your tongue to make a slide from the jaw to the lower lip, and the tongue should be lifted up further inwards, so that the airway is narrower and the airflow is lifted up.
Two fingers act as sides, I usually put my fingers against the tip of the tongue, the nail surface and the fingerprint surface can be used, leaving space in the middle, and the mouth is picked up but not too much.
The tip of the tongue can be parallel to the lower lip or placed on the lower lip, pay attention to blocking the corners, forming the same space as the inside of the whistle, the middle is not used, the part of the air is the same, it feels like a three-dimensional isosceles trapezoid.
The principle is that the tongue and fingers form a barrier between the lips, so that the qi can only pass through the gap of the lips.
Blowing air must feel itself, the air flow must first be stable, and if you want to blow, you must be stable and strong.
If you can whistle without your hands, it may be easier to blow.
The whistle without fingers is the tip of the tongue against the lower teeth, the middle and back of the tongue are raised and reduced, the lip exit should also be reduced, and the whistle without the hand cannot be too loud, and the tongue will go out of shape with a force.
The angle of the hand should look at the surface shape, if your upper jaw protrudes and blows out of the airflow, the fingers should be parallel to the airflow, that is, the hand is tilted down.
Similarly, if the jaw is protruding, the hand is tilted upwards.
Up and down is almost horizontal.
The description may be wrong, but it is easy to learn by studying the structure of the whistle.
It's like a tongue-beating like a suction cup pulled off the wall, except that there is an additional link in the compressed air of the tip of the tongue.