?  Library of Wonders The Wonder of Sound

Why can we talk through a telephone?

Have you ever played with a string telephone? You can make one by joining two paper cups with a tight string. If you talk into one of the cups, the other person can hear your voice in the other cup. But it’s impossible to talk to people far away with a string telephone. Walls get in the way, and the string can’t be super long.

So why can you talk to people far away with the telephone in your home? The reason is the sound is carried by changing it into electric waves. Why can we talk through a telephone? The paper cup in a string telephone carries the vibrations of your voice along the string. In the same way, the diaphragm in the telephone picks up the vibrations of your voice. The difference is a telephone wire replaces the string. Your voice is changed to electric waves that are carried along the telephone wire. This is how your voice reaches the other person far away almost instantly. The electric waves that reach the other person vibrate the diaphragm in their telephone, so they can hear your voice.