So the other day I held the phone up to my ear with the speakerphone turned on and I realized that I could actually feel the air on my face as the person talked. This initially seemed creepy but eventually I came around to the idea that it’s not like the phone was breathing but the variances and vibrations were enough to move the air in a way I could feel. It made me think of speakers, which really are pretty nifty little inventions.
A microphone and a speaker are basically the same thing. The construction is different enough that a speaker makes a poor microphone and a microphone makes a poor speaker. But the idea is the same either way. There’s a basic translation between the vibrations of a thin membrane and a magnet. With a microphone, the magnet moves because the membrane vibrates, and with a speaker the membrane vibrates because the magnet moves. Either way, it’s a very elegant way of translating movement into electricity. It’s so elegant that a really good speaker can reproduce the most delicate nuance.
See, the world today is mostly digital. It’s kind of easy to think about how computers deal with sounds. It’s all math. Each slice of time represents a specific frequency of sound – combine them in the proper order and you get a song. Manipulate them by changing the math. But it’s a little harder for us to really grasp the analog nature of speakers. It’s all about waves and variances and magnetism and vibrations. It’s the stuff that real scientists mucked around with 150 years ago, and they did it without computers or even electric lights. You just had a few guys like Elisha Gray and Alexander Graham Bell who were experimenting with the idea that you could convert sound into electricity and back. They didn’t know what they were doing, and they sure didn’t know how much they’d change the world.