What was happening to the balloon when you hold it front of radio speakers?

When you hold a balloon in front of radio speakers, the sound waves produced by the speakers create vibrations in the air. These vibrations cause the balloon's surface to move, making it appear to bounce or sway. Additionally, if the balloon is inflated and has a light surface, it may even visibly expand or contract with the sound waves, demonstrating the interaction between sound and air pressure. This phenomenon illustrates how sound can exert force on objects in its vicinity.