Aww - here I was thinking this was going to be "what was the first digitized audio you ever made"; kinda disappointed!
Oh well - here's mine: Way back in the mid-1980s, Radio Shack used to have a magazine dedicated to their microcomputer systems they sold. Inside one of the issues was a little machine language program that you could put on a Color Computer 2 (which I owned, thanks to my parents) that would turn on the cassette tape motor, read in a second or so of sound, digitize it to memory (like at 1-2 bits per sample - it was pretty awful), then play it back out the TV speaker. It sounded terrible; I don't remember what I sampled first, but it was likely my Styx Roboto tape...
Ok, some of you old farts out there - surely someone here digitized some sound to punch cards or something, right?