Making Cup Phones

We didn't know much science about how sound travels when we were in primary four or so, but I could swear that we carried out some high tech projects that could pass for a scientific award; One of those projects was when we made our own own phones!  I don't know how we landed upon the technology but what I remember is that it worked so well, that I and some playmates always escaped from all other activity to do cup phones in the back yards.We made  tin can and string (or cup and string) telephones and spoke to each other through them a good distance apart; Even whispers could be heard through those cup phones .

Cup Phones

It workded like this; We looked for two empty tins or cans, especially plastic ones like thrown cups, jelly containers, disposable coke cups etc... and a long piece of string -the longer the thread the more fun...

We would punch a tiny hole at the bottom of each can, just enough for the string to fit through. If the plastic cup was too thick for whatever sharp tool we were using, we looked for a pointed metallic  pin and put it in a fire for a minute, then just put it through the bottom of the cup, and the holes would be created, only large enough to put the string through.

Then we pushed the string through the bottom of each can, using the end of a thin clip, or threaded it through with a small wire. Then tied a knot with the string inside the cup -the knot resting firmly in the bottom of the can. We could tie the string knot around a little piece of a stick, like toothpick but not exactly a toothpick, to get the string to stay hooked in the cup.

We then placed the second end of the string through the bottom of the other can or cup, as we did the first - tied a knot as before, and put the string tight in both cans. 

The finished phone looked something like this, but this one is short and not straight

One of us would now hold one can and move to the full distance of the string, then placed the open end of his can over his ear and the the other would speak into the open end of the other can. The string had to be as tight as it could be straight, without breaking it. When it was made correctly, you could hear your friend speak, from wherever he was, over a long piece of string. Then, you could also talk while your friend listens.

You could argue that, with that technology in our hands, we had the ability to install cup phones 

in homes, criss-crossing rooms, and charge freakin cup bills; 

The Japanese had nothing on our Cup Telephones.