The history of cinematographic technique is far more complex and unknown than one could imagine. And in this domaine, the chapter on evolution – often confused and chaotic – of sound systems is largely still to be written. It is not only a matter of the years preceding the formal birth of “sound-on-film”, but also of the following period. We should not forget, in fact, that film industry lacked of a common standard for many years, and that evolution of radio and in general of sound technology (microphones, recording apparatuses, amplification, loudspeakers…) took place in a very chaotic way. Endless were the systems devised and used in order to improve the quality of the sound, to create or imitate stereophonic sound. The wonder of the “sound film” was also the wonder of “wonderful” systems.

In this complex domaine, sometimes great surprises are found. it is the case of Citizen Kane. Few people knew, until know, that Welles’ film were produced by using one of those weird sound system, which had a large, although short success. In this case, the system was meant to reduce the background noise and to improve the dynamic of the sound.

Such a discoveries (or re-discoveries) impose serious thoughts about the way we are forced to see and hear films from the past. In facts, it is evident that a faithful reproduction of such an event as cinematographic projection of (e.g.) Citizen Kane implies the recreation of a complete sound system: from amplification to loudspeakers.

Therefore, in this case, the study and research centre Cinévolution, Mons (Belgium), has elaborated a decoding circuit which allows for the reproduction of this particular type of recording onto a conventional system (just so long as the existing sound system is of good quality, so as to be able to stand the modulation peaks which may go over 9dB more than the normal level of a sound system). In collaboration with the Cineteca del Comune di Bologna, we have provided the cinema Lumière with an original Western Electric speaker in accordance to the Academy AO M-2 characteristics, and also a particular circuit which adapts this old standard and which decodes the additional system of reduction of non-complementary noises, a factor which constitutes the peculiarity of this system in which background noise, typical of optical recordings, is reduced to 6dB.