We talk into microphones
and listen through headphones. But both of these devices
use a special membrane to do their job. The membrane inside of a microphone
is used to capture sound that is then sent through wires as an electrical signal. And inside a pair of headphones, a membrane helps
turn that electrical signal back into sound. So it turns out that a microphone and headphones
are built in a very similar way even though they are used quite differently.