Veteran Irish broadcaster Gay Byrne always said that radio was more person-to-person than television: on TV, you're speaking to masses. On radio, you're communicating with just one person at a time.
TV was the communications revolution of the late 20th century, but radio has survived very successfully and internet listening has given it an entirely new dimension.
I've now been introduced to an innovative form of radio - radio stations around the globe, which you can tune into at any time via a website called Radio Garden. You just click on Radio Garden via Google and up comes a physical image of Planet Earth, dotted with little green lights in various locations.
Press one little green light and you can be in Santa Monica, California. Click on another and you can be in Polynesia, listening to a rather sweet version of French on Polynesie FM 95.02.
Zoom across to India and hear the great hits from Bollywood. You have at least four Vatican radio stations in Rome - RV1, 2,3,4, (there's theoretically two more) - where you may listen to speech in Chinese, or Portuguese, or other languages, or sacred music.
Flash back to Odessa in Texas, to FM Nuuk in Greenland, to West Cork FM, to France Inter, to Kawawachikamach in Quebec, Canada. Truly we can now, like Ariel, encircle the globe in a flash.
Radio Garden can also be a lesson in geography. Because the picture of the globe is just physical, you might need an accompanying political and topographical map to name the locations.
You can forget just where New Zealand is, or how enormous is Canada and its outlying islands. Radio Garden gives you the twinkling green dots for radio stations on a physical earth, though you can also do a search for a particular place.
Radio stations, on this version of Planet Earth, are distributed unevenly. Europe is crowded with radio, but there isn't a lot on the Arabian Peninsula, save for Kuwait Radio (some cheerful-sounding conversation in Arabic, with much "Salam Alaikum"), Abu Dhabi and Riyadh (featuring Arabic music).
Obviously, language is a barrier and only Spanish speakers might access the many radio stations in Latin America, or Chinese speakers venture into radio from China, although there is music everywhere.
And Radio Garden does seem more orientated towards music, which is not only a universal language, but often a universal sound.
Is this a welcome form of globalisation? Or a depressing sign that a bland sameness seems to be taking over everywhere?
The rock, pop and disco-dance music, to my ears, seems exactly the same from Community Radio Castlebar as from Cruise FM in Te Kuiti, New Zealand; Slice Audio in Belfast sounds pretty similar to Deep Dance Radio in Amsterdam - where I tuned into a frenzied kind of rock.
Papua New Guinea's (Port Moresby NAU FM) music choice, though sometimes announced in pidgin, seems hardly different from BBC Radio 1.
A salient exception seems to be India, where Indian popular singing-dancing music wafts forth from many airwaves, its singular composition and high-pitched female notes being its own genre. Good for them for enjoying their own cultural traditions.
Obviously, in surfing the world's radio stations, you're just catching a moment in time - getting a flavour of what they are offering.
There are, to be sure, different genres in music - gospel, country, and even Irish music as a special interest. In St John's, Newfoundland, the charmingly named Voice of the Common Man radio (VOCM) has an Irish requests slot, with plenty of harmonica and fiddle.
New York (which offers 203 stations) has The Great American Songbook radio channel. Japan has golden oldies on J1 Gold. And Pretoria in South Africa has what must be one of the most cultured radio stations in the world, entitled Just Playing Haydn.
As there are universal sounds in music, there are also global themes in talk radio. It won't surprise anyone that conversations around Covid, the vaccines, the care workers, how long the lockdown will last, what the impact is on children and students, are heard everywhere.
The phrase "We're all in this together" is uttered from Vancouver to Melbourne. Evidently, world news, local news, crime, traffic and weather are common features, but as a topic, Covid still reigns supreme.
Stations with specialised interests have their own focus. In New York, Bloomberg AM 1130 deals in stocks, shares and all kinds of money news - probably informative for people with a close interest in financial matters. Fox News Radio, also in New York, provides the listener with plenty of conservative hard talk, often delivered in those confident Tucker Carlson-like male voices.
The most polished vocal presentation I heard came from Utah - so polite and clear: you could just imagine those clean-cut Mormons on Salt Lake City KUER-FM.
It's fascinating to hear voices from all over the world and maybe that image of Earth does imply that, "We're all in this together."
Oh, brave new world that has such wonders in it!