Tin can telephone

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A tin can telephone is a type of voice-transmitting device made up of two tin cans, paper cups or similar articles attached to either end of a string. This device can be made easily with two tin cans, each with the top removed and a hole punched into the other end of the can. The hole allows tying a string (about the gauge of a kite string) or wire between them. When the string is taut the vibrations made by speaking into the cup can travel along the string and be heard at the other end.

In the centuries before tin cans and paper cups became commonplace, other cups were used and the device was sometimes called the "lovers' telephone". During the 20th century, it came into common use in preschools and elementary schools to teach children about sound vibration. Uses have also been recorded among neighboring high school students as an alternative to simply yelling back and forth.^{[citation needed]}