As shown in Schafer — The Tuning of the World, McLuhan described Murray Schafer’s work at some length in a presentation to UNESCO in 1976. He and Schafer had long been aware of one another (ever since Schafer studied at the University of Toronto in the early 1950s)¹ and then got back in touch decades later as illustrated in a December 16, 1974 letter from McLuhan to Schafer:

Dear Murray,
Naturally I approve entirely your approach in soundscape. We are living in an acoustic age for the first time in centuries, and by that I mean that the electric environment is simultaneous. Hearing is structured by the experience of picking up information from all directions at once. For this reason, even the telegraph gave to news the simultaneous character which created the “mosaic” press of disconnected events under a single date-line. At this moment, the entire planet exists in that form of instant but discontinuous co-presence of everything.² One hidden dimension of the soundscape is to be found in Rock music, which pours the sounds of the city through the rhythms of the English language as a means of humanizing metropolitan cacophony . The role of music as humanizing technological noise by processing it through the regional dialects, seems to have been ignored by all musicologists. Rock can only be sung in English , and for that reason the Chinese and the Africans and the Hindu learn English so they can sing Rock. The radio soundscape, earlier, had brought forth jazz, which also depends entirely on the rhythms of the English language, especially its Southern and oral manifestations.
In a magazine called Listening (University of Chicago Press, vol. 9, nos. 1 & 2, Winter/Spring, 1974, p 9-27 ), I have a recent essay explaining in what senses the medieval period was acoustic right up to the edge of the Gutenberg, or visual, revolution. Huizinga, in The Waning of the Middle Ages (1954), explains some of it, and Siegfried Giedion in Mechanization Takes Command has a section on medieval comfort, in which he explains that a medieval space was furnished even when empty, because of its acoustic properties.
If you can manage to interest psychologists in the nature of acoustic space, you would be doing a good work. What they, and all scientists, call “space” is simply visual space, which is continuous and connected and static. Scientists and architects alike refer to this as “physical” space. It is the space which can be divided and quantified, measured and tabulated. Acoustic space cannot be divided or connected, and it is certainly not static but dynamic. Clinging to the remnants of visual space in this new acoustic age has become a kind of a paranoiac state. Personally, I think I prefer visual to acoustic space, but this should not be a matter of either/or. In his Responsive Chord, Tony Schwartz explains how the TV image uses the eye as an ear (on page 14). (Incidentally the book was published by Doubleday, N.Y. in 1973.) The rapid disappearance of literature is directly related to this factor.
Had you ever thought of surveying the poets for some of their awareness of the soundscape, starting with the opening of Chaucer’s Prologue to the Canterbury Tales, and onwards? I think you will find direction and perception in this matter. Let me urge you to put some of this material into your Tuning of the World . Would be glad to help.³