On a radio station around here -- one of the few AM stations I can receive during daylight hours, I'm way out in the sticks -- there's this little segment that comes on in the morning while I'm eating breakfast.
Two fellows talking, most of it inconsequential chat. One guy is in the studio, and the other is very obviously talking over a phone line, audio quality none too good. Chat, and some of it is, Mr. Studio will pose questions and Mr. Phone Line will ramble on with long, wandering, gaseous replies. Actually Mr. Phone Line does the bulk of the talking.
And here's the thing: I can tell how Mr. Phone Line looks. He wears sunglasses with big silvered lenses. He's got black hair, but with a severely receding hairline, and the hair on top of his head is thinning out. He wears a nylon windbreaker. Big forehead, with prominent creases in it. Bad teeth, and nicotine stained.
How can I tell? By the sound of his voice. Anyone with a voice like that has got to look like that. Even over a mediocre phone connection, by his voice you shall know him.