Description of Parabolic Sound dishes
Goldsmiths
College
The sound dishes are a pair of gigantic curved reflectors, that sends and collects sound across the room. The parabolic dishes (curved shaped) are essentially a mirror telescope for sound.
What Happens?
One person talks or makes a sound in to the focus on one dish, the soundwaves are then bounced across the room. When they reach the second dish the sound waves will bounce on the dish and converge toward the focus. The concentration at the focus means the person at the second dish hears the sound made by the person at dish one. The reason for this is because the curved shape of the dishes allows the sound to focus.
A parabolic surface has the interesting property that all sound waves that disseminate parallel to its central axis travel the same distance to get to its focus.
That means that when you aim the dish at a distant sound source, all the sound bounces off the dish and converges towards the focus in phase, with its pressure peaks and troughs synchronised so that they work together to make the loudest possible sound vibrations. The sound is thus enhanced at the focus, but only if it originated from the source you are aiming it at .