Radioed ahead
As these hyperlinks amply illustrate, radio didn't take long to become accepted as a vital medium and an important form of communication. Newspapers, once they overcame their suspicion of this new rival, began publishing a radio guide. Radio stars appeared on television. As did radio announcers (which is who I was thinking of when I first thought of 'radio stars'). Those working in radio became characters in a TV series. Live audiences turned up for radio plays. Radio has been the subject of 'major motion pictures' as they call them in the industry.
As to when a radio, in whatever iteration, first appeared in the background on stage or on the set of a television sitcom, I leave it to other bloggers to discover.
So radio has reached us through all these other media and has played an important part in its own right. Having the added advantage of being perfect for self-reflexive promotion of the continued importance of radio. No messy visuals to distract you. Look into my ayes.
There were academic papers laying the ground for radio broadcasting and books documenting its rise. Journals saw it worthy of serious study and magazines as a form of entertainment to discuss, promote or share details about.
Did it come across in the early Internet nineties? It was a feature of newsgroups and then message boards and (finally?) social media.
The postmodernism that blasted out from campuses all but assured us of a postmodern assertion of our own right to broadcast. Did I say postmodern?