Focusing of sound

HOW

1. Two people are needed to perform this experiment.
2. Stand by the two parabolic antennas where the feet are marked. Try to talk facing each other.
3. Then turn towards ‘your’ antennas and attempt to talk again.

WHY

When you are facing the antennas, you can talk to each other – even by whispering.

The sounds produced propagate through space as sound waves. When the transmitter – receiver distance increases, their intensity rapidly decreases. The antenna to which you are speaking reflects the sound waves directed at it. These are then passed on to the other one. Its parabolic shape means that the re-reflected waves are additionally focused. If your ears are at the focus of the waves, which we call the focal point, then you hear an effectively amplified sound.