Between 1920 to 1930 he invented, patented and improved upon a system of recording a sound track on a strip of film, thus allowing accurate synchronization with the picture. Lee de Forest invented the Talking Motion Picture.
Decades of de Forest
Following a solid Yale education in Physics and Electricity, he spent the decade between 1900 and 1910 improving the wireless telegraph, but he quickly tired of its limitations of sending coded messages. In 1906 he filed his first patent for the vacuum tube he called the Audion, describing it as a detector of sound. By 1907 he had invented an arc-based radiotelephone transmitter and Audion receiver, and he was writing about the possibility of sending music into homes by wireless.