How Do Telephones Carry Voice?

What You'll Learn

• When you speak, your voice makes sound waves in the air
• A microphone in the phone catches the sound waves
• The phone turns sound waves into electric signals or radio waves
• The signal travels to another phone through wires, towers, or satellites
• The other phone turns the signal back into sound you can hear

Words to Know

Telephone

A device for talking over a distance

"I called my grandma on the telephone."

Microphone

The part that picks up sound

"The microphone heard my voice."

Signal

A coded message sent somewhere

"The signal carried my voice to another phone."

Speaker

The part that turns signals into sound

"The speaker played my friend's voice."

Check What You Learned

Fun Facts

• Telephones convert sound waves into electrical signals using a microphone/transducer

  Source: Britannica / telecommunications

• Analog signals vary continuously with sound pressure; digital phones sample sound into numbers

  Source: HowStuffWorks

• Signals travel through copper wires, fiber-optic cables, cellular radio towers, and satellites

  Source: FCC / telecommunications overview

• Cell phones transmit radio-frequency signals to base stations, which route calls through networks

  Source: CTIA / cellular basics

• At the receiving end, a speaker converts electrical signals back into sound waves

  Source: Britannica

• Alexander Graham Bell made the first telephone call in 1876: "Mr. Watson, come here — I want to see you"

  Source: Library of Congress