Book 1, Question 118
How Do Headphones Make Sound? Shaking Air Into Music!
Music from headphones starts as electricity. The music player sends an electrical pattern through the cable that matches the song, and that pattern makes a coil and magnet push and pull super fast, shaking a speaker cone in and out. The moving cone pushes the air beside it, those vibrations travel to your ear, and your brain turns them into music. The page says sound is moving air, not magic in the cord. Gently touch a speaker cone to feel it move.
From the book
Page from A Million Whys Book 1
More fun facts
- Headphones contain tiny loudspeakers.
- Inside a speaker, an electromagnet and a permanent magnet push on each other, moving a cone.
- Music is sent as alternating current, which keeps flipping direction, so the cone moves in and out very fast.
- The moving cone squeezes and stretches the air, making sound waves that travel to your ears.
- NASA scientists invented a magnetic liquid called ferrofluid, filled with very tiny bits of iron oxide, to help move rocket fuel.
- Ferrofluid later ended up in loudspeakers, and in 2012 Sony used it in slim speakers it said sounded louder and cleaner.
Questions kids ask
Are there speakers inside headphones?
Yes. Headphones contain tiny loudspeakers.
What is ferrofluid?
A magnetic liquid with tiny bits of iron oxide, first developed at NASA and later used in some speakers.