How did a 1930s microphone work?

A 1930s microphone typically used a carbon button or ribbon design to convert sound waves into electrical signals. In a carbon microphone, sound waves would cause a diaphragm to vibrate, compressing and decompressing carbon granules, which varied the electrical resistance and generated an audio signal. Ribbon microphones, on the other hand, employed a thin metal ribbon suspended in a magnetic field; sound waves would cause the ribbon to move, inducing an electrical current. Both types effectively captured sound and transmitted it for amplification or broadcasting.