Georges Sadoul, on his book Histoire du Cinéma Mondial, des Origines à nos Jours, published in 1949, commented on the revolution that had been taking ground, concerning sound:
The flexibility of the magnetic process has allowed to build soundtracks in which the assembly of noise assumes a role as important as the words and music.
I assume I have a good translated version of this book, so considering Sadoul referred to sounds falling outside the dialogue and music box as “noise” is intriguing and laughable at the same time. Anyway, could it have been the turning point when sound technicians started to dig in a sound design world even before they have a word for it? Could these sounds fell, before that time, in a category where they would be simply excluded and thought of as sound pollution due the recording quality and playback issues? Or, if the audiences had been presented with these “noises” since the sound cinema began, would Sadoul even think of those sounds as noises?