They can be found toiling behind the scenes in telephones, hearing aids, tape recorders and PA systems. Most people credit Emile Berliner with inventing the microphone. Specifically, they convert sound waves into electric audio signals using a two-part process. First, the sound waves cause a thin diaphragm inside the microphone to vibrate. Those vibrations trigger a change in an electric current that is then sent out to a mixer or amplifier.
Microphones fall into several categories.
Carbon mikes, for example, appear most often in telephones made from 1915 through the 1920s. Condenser microphones brought us the first audible movies, and the Nazis used them to announce the 1936 Berlin Olympics. In the 1940s, ribbon microphones changed the tone of radio. Today, durable and compact electret mikes are found in camcorders and on interviewers' lapels. So next time Vin Scully recites the Dodgers' lineup or you mimic the vocal stylings of Sheena Easton at a karaoke bar, remember that the microphone makes it possible.