 In 1907, Lauste was awarded the first patent for sound-on-film technology, involving the transformation of sound into light waves that are photographically recorded direct onto celluloid.As described by historian Scott Eyman,

It was a double system, that is, the sound was on a different piece of film from the picture...In essence, the sound was captured by a microphone and translated into light waves via a light valve, a thin ribbon of sensitive metal over a tiny slit.