Personally. I feel quite helpless and panicky as I contemplate the range of new assumptions and frames and parameters which our new technology has imposed upon us.  (NAEB Project, ”MATERIALS DEVELOPED BY PROJECT”)

McLuhan seems to have arrived at his relativity theory of human experience between 1955 and 1960. His coming to understand “acoustic space” as “a means of exploring and defining mental states“ was central to this process.

Here he is in ‘New Media in Arts Education’, an address given at the March 1956 convention of The Eastern Arts Association.

By the time of Baudelaire and Rimbaud the use of painting as a means of fixing a mental state had been pushed very far. Suddenly the visual boundaries yielded to music, and the symbolist poets discovered the acoustic space of the auditory imagination. Let me say at once that this break through from the visual world into the acoustic world seems to be the most revolutionary thing that has occurred in Western culture since the invention of phonetic writing. To understand the human, social, and artistic bearings of this event is indispensable today whether for the teacher or the citizen. Most of the cultural confusion of our world results from this huge shift in the geography of perception and feeling. Let me repeat that the artistic developments which we associate with the Romantics in painting and poetry, had consisted in the impressionistic use of external landscape as a means of exploring and defining mental states. When these artists came to the frontiers of visual landscape they passed over into its opposite, as it were, namely acoustic or auditory space. This unexpected reversal or translation of the visual into the acoustic happened again when the silent movies became sound pictures and again when radio was suddenly metamorphosed into TV. And the consequences of these shifts between sight and sound need to be understood by the teacher today since they turn the language of the arts into a jabberwocky that has to be unscrambled to be understood. When the arts shifted from sight to sound, from visual to acoustic organization of experience, the tempo and rhythm of our culture shifted as though an LP disc were suddenly shifted to 78 speed.

McLuhan is also describing his own experience here in the crucial 1955-1956 time period. To paraphrase: 

Suddenly the visual boundaries [which had constrained me until at least 1954] yielded to music, and [I] discovered the acoustic space of the auditory imagination. This break through from the visual world into the acoustic world [was] the most revolutionary thing [that had ever occurred to me and, now that I had experienced it in myself, I came to believe that it was equally] the most revolutionary thing that had occurred in Western culture since the invention of phonetic writing. To understand the human, social, and artistic bearings of this event [seemed] indispensable [to me since I could now attribute] most of the cultural confusion of our world [to] this huge shift in the geography of perception and feeling.

By 1959 his thinking had advanced to the notion of an “instantaneous (…) information field” in which all possible space-time configurations were arrayed: “Each item makes its own world, unrelated to any other (…) and the assembly of items constitutes a kind of global image in which there is much overlay and montage but little pictorial space or perspective“. Here he is in ‘Myth and Mass Media‘ of that year:¹

Electronic culture accepts the simultaneous as a reconquest of auditory space. Since the ear picks up sound from all directions at once, thus creating a spherical field of experience, it is natural that electronically moved information should also assume this sphere-like pattern. Since the telegraph, then, the forms of Western culture have been strongly shaped by the sphere-like pattern that belongs to a field of awareness in which all the elements are practically simultaneous. It is this instantaneous character of the information field today, inseparable from electronic media, that confers the formal auditory character on the new culture. That is to say, for example, that the newspaper page, since the introduction of the telegraph, has had a formally auditory character and only incidentally a lineal, literary form. Each item makes its own world, unrelated to any other item save by date line. And the assembly of items constitutes a kind of global image in which there is much overlay and montage but little pictorial space or perspective. For electronically moved information, in being simultaneous, assumes the total-field pattern, as in auditory space. And preliterate societies likewise live largely in the auditory or simultaneous mode with an inclusiveness of awareness that increasingly characterizes our electronic age. The traumatic shock of moving from the segmental, lineal space of literacy into the auditory, unified field of electronic information is quite unlike the reverse process. But today, while we are resuming so many of the preliterate modes of awareness, we can at the same time watch many preliterate cultures beginning their tour through the cultural phases of literacy.

How to investigate and communicate this “field of experience” would become the task for the remaining two decades of his life. Here he is attempting both of these in the ‘The Agenbite of Outwit’, 1963:

The all-at-once-ness of auditory space is the exact opposite of lineality, of taking one thing at a time. It is very confusing to learn that the mosaic of a newspaper page is “auditory” in basic structure. This, however, is only to say that any pattern in which the components co-exist without direct, lineal hook-up or connection, creating a field of simultaneous relations, is auditory, even though some of its aspects can be seen. The items of news and advertising that exist under a newspaper dateline are interrelated only by that dateline. They have no interconnection of logic or statement. Yet they form a mosaic or corporate image whose parts are interpenetrating. Such is also the kind of order that tends to exist in a city or a culture. It is a kind of orchestral, resonating unity, not the unity of logical discourse.