Quote:
Originally Posted by PAR_WIG1350
First, the discovery that a moving diaphragm could pick up and reproduce sounds (ears and drums are respective examples that are respectively naturally occurring and well known throughout history). The second was that a current traveling through a coil can move things.
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The first was a Thomas Edison thing - a cone with a diaphragm at the smaller end, the center of which was mounted a needle. As a wax-coated cylinder spun beneath the needle, screaming into the cone transferred the vibrations to the wax. Shellac the wax to harden it, and use the same needle-diaphragm-cone assembly to trace the wax impression, and sound comes out. But only once - the cylinder was ruined by playing it :-(
Of course, that system was eventually optimized a lot. Tinfoil coating, for example.
The second was a Michael Faraday thing, IIRC, but of course it wasn't seriously implemented in practice until amplification came about. But before then* Alexander Graham Bell used a bunch of carbon granules beneath the diaphragm which, when mechanically excited** generated a small current and, conversely, vibrated when electrically excited.
* Emile Berliner actually had the first microphone, the "loose contact microphone", but it wasn't as practical as the carbon granule type, which is still in use today.
**meaning 'have energy put in'. Don't get excited.