In the wake of his encounter with Eisenstein, another film theorist read by McLuhan along with Cesare Zavattini¹ was Béla Balázs (1884-1949). The three together — Eisenstein, Zavattini and Balázs — exercised enormous influence on all of his subsequent work. It is no exaggeration to say that it would not have been possible without them.

Here is McLuhan in late 1953:

[McLuhan] Béla Balázs in his Theory of the Film (1952)² notes some of the changes in visual habits resulting from the printing press on one hand and the camera on the other:
[Balázs as cited by McLuhan] “The discovery of printing gradually rendered illegible the faces of men. So much could be read from paper that the method of conveying meaning by facial expression fell into desuetude. Victor Hugo wrote once that the printed book took over the part played by the cathedral in the Middle Ages and became the carrier of the spirit of the people. But the thousands of books tore the one spirit . . . into thousands of opinions (…) tore the church into a thousand books. The visual spirit was thus turned into a legible spirit and visual culture into a culture of concepts. (…) But we paid little attention to the fact that, in conformity with this, the face of individual men, their foreheads, their eyes, their mouths, had also of necessity and quite correctly to suffer a change.
“At present a new discovery, a new machine is at work to turn the attention of men back to a visual culture and to give them new faces. This machine is the cinematographic camera. Like the printing press it is a technical device for the multiplication and distribution of products of the human spirit; its effect on human culture will not be less than that of the printing press. (…) The gestures of visual man are not intended to convey concepts which can be expressed in words, but such (…) non-rational emotions which would still remain unexpressed when everything that can be told has been told (…) Just as our musical experiences cannot be expressed in rationalized concepts, what appears on the face and in facial expression is a spiritual experience which is rendered immediately visible without the intermediary of words.”
[McLuhan] The printed page in rendering the language of the face and gesture illegible has also caused the abstract media of printed words to become the main bridge for the inter-awareness of spiritual and mental states.³ In the epoch of print and word culture the body ceased to have much expressive value and the human spirit became audible but invisible. The camera eye has reversed this process in reacquainting the masses of men once more within the grammar of gesture. Today commerce has channelled much of this change along sex lines. But even there the power of the camera eye to change physical attitudes and make-up is familiar to all. (‘Culture Without Literacy’, Explorations 1, 1953)

In 1954 the culture and communication seminar would take new direction from the topic of ‘acoustic space’. But the shock of recognition registered there through the comments of Carl Williams,⁴ together with suggestions in the work of McLuhan’s mentor, Sigfried Giedion,⁵ was surely (given the acquaintance of McLuhan and Theall with Theory of the Film)⁶ mediated through the chapter on ‘Sound’ in Balázs:

The Acoustic World⁷
It is the business of the sound film to reveal for us our acoustic environment, the acoustic landscape in which we live, the speech of things and the intimate whisperings of nature; all that has speech beyond human speech, and speaks to us with the vast conversational powers of life and incessantly influences and directs our thoughts and emotions, from the muttering of the sea to the din of a great city, from the roar of machinery to the gentle patter of autumn rain on a window pane. The meaning of a floorboard creaking in a deserted room, a bullet whistling past our ear, the death-watch beetle ticking in old furniture, and the forest spring tinkling over the stones. Sensitive lyrical poets always could hear these significant sounds of life and describe them in words. It is for the sound film to let them speak to us more directly from the screen. (Theory of the Film, 198)⁸

Balázs continued this passage in a way that not only would have recalled Giedion’s Space, Time and Architecture to McLuhan, but that may well have first sparked Giedion’s own thoughts along these lines (presumably from the original German of Balázs) sometime before the appearance of STA in 1941:

The sounds of our day-to-day life [continued Balázs] we hitherto perceived merely as a confused noise, as a formless mass of din, rather as an unmusical person may listen to a symphony; at best he may be able to distinguish the leading melody, the rest will fuse into a chaotic clamour. The sound film will teach us to analyse even chaotic noise with our ear and read the score of life’s symphony. Our ear will hear the different voices in the general babble and distinguish their character as manifestations of individual life. It is an old maxim that art saves us from chaos. The arts differ from each other in the specific kind of chaos which they fight against. The vocation of the sound film is to redeem us from the chaos of shapeless noise by accepting it as expression, as significance, as meaning.⁹

Here is Giedion from the start of STA:

In both contemporary science and contemporary art it is possible to detect elements of the general pattern which our culture will embody. The situation is a curious one: our culture is like an orchestra where the instruments lie ready tuned, but where every musician is cut off from his follows by a soundproof wall.