Voicepipe (acoustic telegraph)

What can you do here
Two people are needed to perform this experiment. Stand next to both ends of the device and try to talk using the ‚telegraph’. When one person is speaking to the funnel - shaped piece, the other is putting their ear to the receiving end to hear the words. Try whispering.

Then, try to talk to each other directly (not using the device) without changing your places. 

How does it work
In an unlimited space the soundwave travels in all directions and its intensity quickly decreases with the distance. The pipe is a waveguide, a conveying structure that directs waves to the receiver, i.e., your ear.

Why is this happening
Voicepipes or speaking tubes were used to communicate, e.g., on ships, in fortifications, offices, mansions. They have been superseded by telephone systems.