This is one of the wackiest of them all. This is ability is wacky to the point of later having been outright denied in other sources. Early on in the history of the comic, Daredevil’s radar sense was often depicted as a kind of internal, all-purpose radiation/radio signal detecting device rather than as the simple, yet powerful, “proximity sense” we are used to seeing today. In the panel below, the idea of detecting a radio signal was taken a step further, however, to the point where Matt is not only sensing the presence of a radio signal but actually hearing the message! The below is from Daredevil #10, written and penciled by Wally Wood, also reprinted in the second Daredevil Annual from 1970.
Matt is shown against a faded party scene background, the focus is on his face and there are concentric circles drawn around his head to illustrate that he is using his radar sense. He thinks to himself, “What’s that?! My radar hearing has picked up a radio message! It’s being transmitted from this yacht!” We then read the content of the transmission: “Organizer to Frog Man… The time has come for our next move…”
I think Matt is probably grateful he doesn’t actually have this ability. Can anyone imagine the agony of picking up every radio signal going through the air on every frequency? I think most of us would probably pass on that one. For the rare science geek who might be interested in how a radio receiver actually extracts the message from a radio signal, here’s a nice pedagogical chart. Enjoy!