Sound waves
A sound is formed when the air is made to vibrate. As a result, sound waves are produced. They can be produced in various ways. A small, long leaf can be used to produce a simple sound. When it is held tightly between the thumbs of your hands and movement is blown to it, the result is a sound.
The leaf of a reed is perfect for producing such a sound. However, a similar sound can be achieved even with blades of grass or a small piece of paper.