Question

how is the sound produce by whistling

Answer 1

As the air reaches the other, closed end, all the air molecules "pile up" on top of each other and cause a high-pressure region. The air escapes out the little hole in the end, making thenoise you hear. The frequency of thesound is dependent on the length of the whistle.

Answer 2

When you blow into a whistle, you are forcing air through a narrow windway which results in high pressure of air. As it leaves the windway, the high pressure air oscillates, and a standing wave pattern in the whistle is created, amplifying the sound. Basically, it makes the air vibrate.