It was an accidental discovery. Edison was researching and improving the telegraph machine one day, a monotonous sound got his attention, it was from the machine. He discovered that the machine had different sound while he typed on the paper with different force. Thereby, he had a suppose, can a carrier in motion with different channels create different sounds?

Another time when Edison was testing telephone, he noticed that plate of telephone would vibrate with the sound from the other side, he used a pin to test it, the regular rule was founded after this experiment. After few months of creations and improvements, a basic phonograph prototype had been created, the first phonograph.

'This is a machine that can speak.'

An odd machine with large cylinder, sound receiver and sound plate. In the final experiment, the song 'Mary Had A Little Lamb' sang by Edison was replayed from the machine peacefully...

During the early periods of phonograph, Edison changed and improved the phonograph constantly for better performance, for the next fifty years, old and deaf Edison continued his efforts on phonograph until he died. 

For the next one hundred and forty years, the massive waves of inventions those lifted by Edison's phonograph are meaningful and significant to the human history. From electric gramophone to magnetic tape sound recorder, from magnetic tape video recorder to laser recorder... With their appearances, to retrospect the origin, isn't that all from the grand invention of Edison?