A New Process for Developing and Printing Photographic Sound Records
Jochen Engl · Transactions of the Society of Motion Picture Engineers · 1927
At the present time quite a number of different methods are known how to record and reproduce sound waves for the purpose of the so-called talking film. With most of these methods the sound variations are photographed on a moving film-strip. Corresponding pictures and sounds being recorded on one common carrier, the synchronized reproduction of both picture and sound records can never be questioned.