History of Audio!. By: Mayten Lumpkin . First sound recorder.
By: Mayten Lumpkin
In 1857, Édouard-Léon Scott de Martinville invented the phonautograph, the first device that could record sound waves as they passed through the air. It was intended only for visual study of the recording and could not play back the sound. The recording medium was a sheet of soot-coated paper wrapped around a rotating cylinder carried on a threaded rod. A stylus, attached to a diaphragm through a series of levers, traced a line through the soot, creating a graphic record of the motions of the diaphragm as it was minutely propelled back and forth by the audio-frequency variations in air pressure.
1921The first commercial AM radio broadcast is made by KDKA, Pittsburgh PA.