possible sound changes:
The short windway is less air-stabilizing than a conventional long recorder beak. Changes in the mouth position of the player have a more direct effect on the sound. Overtones and noise can be influenced much easier.
The beak is so short that when playing with the upper lip, the upper part of the labium can be partially covered. This allows a controllable pitch with the upper lip which is compensated by more breathing pressure. So the sound becomes louder at the correct pitch. The timbre can be influenced as well.
there are two ways to play pianos:
1. let some air escape
The second windway is so short that the pitch increases by variably releasing the opening with the lower lip. This allows a lower lip controllable pitch increase, which is compensated with less breath pressure. So the sound becomes quieter at the correct pitch.
2. blow a control wind
The second windway changes the sound production. If the change is applied selectively, the sound can be changed. Charming pianos are possible as well as ethno-like sounds at the correct pitch.
If you can change the sound that means you have to control by the mouth!
Similar to a modern flute, the sound becomes noisy if you do not understand how to blow the wind stream "cleanly" into the instrument. The position of the teeth, tongue and lips affect the wind flow. The mouth is wide, an O should be formed.
As a test blow strongly and NOISELESSLY towards the hand, 15 cm in front of the mouth, so that you hear only the impact of the wind on the hand. You have to transfer this mouth position to the instrument.
Guide how to play the piano without the new option of air escaping.