I bet he did like a CB'er around here used to do 35+ years ago. He would talk on one radio and listen to himself on another one setup on a power supply. He would control the feedback squeal with the volume on the monitor radio. Of course sometimes he would record himself while talking and then play it back when he had to go to the bathroom or mix another Coke-a-nola.
Yep, that is exactly how he described it. So what you're saying is that "Triple Echo" wasn't the only guy that figured this out? Darn, what a let down...I was sure that I ran into the "inventor of talkback"