Sound focusing

What can you do here
Two people are needed to conduct this experiment. Stand in front of both parabolic antennas where the feet are painted and try to talk face to face. Then turn towards your antennas and try to hold a conversation again.

How does it work
It turns out then when we face the antennas, we can easily hear each other - even if we whisper. Sounds each of us makes travel in space as soundwaves. As the sender - recipient distance increases, the sound intensity quickly diminishes. However, when we talk to the antenna, it reflects the soundwaves and directs them towards the other antenna, whose parabolic shape makes the reflected waves focus. If we put our ears in the spot where they converge, called the focal point, we will hear strengthened sound.

Interesting facts
Elliptical-section surfaces provide another example of objects that focus soundwaves. They were used in building chambers where it was possible for a person in one focus of the ellipse to eavesdrop on people talking in the other focus.

Reflecting soundwaves and focusing them in one point is also a task of the pinna. The focus is, in that case, the auditory canal. The conclusion is simple: the bigger the ears, the better the hearing.