Radio affects most intimately, person-to-person, offering a world of unspoken communication between writer-speaker and the listener. That is the immediate aspect of radio. A private experience. The subliminal depths of radio are charged with the resonating echoes of tribal horns and antique drums. This is inherent in the very nature of this medium, with its power to turn the psyche and society into a single echo chamber.

(Understanding Media, McLuhan)

“ … misunderstanding of the nature of the medium rendered the restraining policies [the press criticising radio and tv] quite futile. Such has always been the case, most notoriously in government censorship of the press and of the movies. Although the medium is the message, the controls go beyond programming. The restraints are always directed to the “content,” which is always another medium. The content of the press is literary statement, as the content of the book is speech, and the content of the movie is the novel. So the effects of radio are quite independent of its programming.”

(Understanding Media, McLuhan)

If we sit and talk in a dark room, words suddenly acquire new meanings and different textures. They become richer, […]. All those gestural qualities […] come back in the dark, and on the radio. Given only the sound of a play, we have to fill in all of the senses, not just the sight of the action. So much do-it-yourself, or completion and “closure” of action, develops a kind of independent isolation in the young that makes them remote and inaccessible.

(Understanding Media, McLuhan)