We've covered most of the basics of how sound is produced and transmitted, but we've left something out, and that's all the electronic devices we use to amplify sound, reproduce it, or get it from one place to another. How exactly does a CD player work? How does a phone work? And how exactly do those two listening devices we carry on either side of our head work? No, not headphones, even though it might seem that some kids do have those permanently attached. The item in question is our ears.