How Does My Voice Carry over the Telephone?
When you speak into a telephone, the sound of your voice causes a thin metal plate inside the mouthpiece to vibrate back and forth. This plate, which is called a diaphragm, is part of an electrical circuit.
It changes the sound waves of your voice into electrical signals that travel over the telephone wire to another telephone, where someone is listening.
There the electrical signals cause another diaphragm inside the receiver to vibrate, producing sound waves similar to those of your voice. As a result, the listener is able to hear what you are saying.