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De Forest pioneering Phonofilm. US inventor and electrical and radio engineer Lee De Forest (centre right, 1873-1961) filming in Phonofilm in 1924 in the grounds of the White House, Washington DC, USA. De Forest patented the Audion tube (triode valve) in 1907, a device that gained widespread use in radios to amplify weak signals. He also invented and worked on a process to record sound directly onto film, a process he called Phonofilm, patented in 1919. This led to the use of sound in films, revolutionising the medium. His awards included the Elliott Cresson Medal of 1923, and the 1946 IEEE Edison Medal.
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