Seeing Sound
How It Works
The things are placed as shown. Then a flashlight is switched on and pointed towards the tight rubber end of the plastic drum. A white poster beard is kept perpendicular to the rubber end. When we speak through the funnel the sound comes out of the other funnel and creates vibrations in the balloon. The vibrations are transferred to the aluminum foil. Consequently the light reflected from the aluminum foil vibrates more if we speak loudly and less if we speak softly. In this way we can see sound.