When was Lee de Forest born?
Lee de Forest
From October 1921 to September 1922, de Forest lived in Berlin, Germany, meeting the Tri-Ergon developers (German inventors Josef Engl (1893–1942), Hans Vogt (1890–1979), and Joseph Massolle (1889–1957)) and investigating other European sound film systems. In April 1922 he announced that he would soon have a workable sound-on-film system.[42] On March 12, 1923 he demonstrated Phonofilm to the press;[43] this was followed on April 12, 1923 by a private demonstration to electrical engineers at the Engineering Society Building's Auditorium at 33 West 39th Street in New York City.