I have a hard time explaining about how MP3's is just a compressed format for music...
If I may, make it visual. Get an old-fashioned print newspaper, the kind where photos are "print screened", where they're made up of tiny dots. Get a magnifying glass and show him one of the photos. First, on the page in actual size, and then through the magnifier so all the dots composing the photo are obvious.
"Can you see the dots?"
"Sure." "When I pull it away, can you still see them?"
"Yes, though it's harder." "But you can still tell what the photo's about, right? You get the big picture?"
"Yes."
Now show him a high-resolution photo taken with a quality camera. No dots, just one coherent image. (Or if there are dots, they're so small, and packed so closely together, that it appears to the eye like a solid image.)
That's the difference between an MP3 and an analog medium like vinyl records or audio tape. (And though a CD is still digital, the data's so tightly packed that it approaches the density of an analog medium.)
In an MP3 file or an audio stream, the music is sampled multiple times a second and converted into the numerical equivalent of a dot. That number is then stored, as is the next dot and the next, and so on. And on playback all those dots are reassembled into something that approximates the original music. But it's an approximation, and that's the key difference. The more times a second you sample, and the more bits you throw into representing that sample, the closer to the original it will be. But it's always just an approximation, like that dot image is to the original photo. But the photo, or the analog recording, represents an actual original.
The downside of analog is it's subject to distortion. Making copies introduces noise, or artifacts, or some other degradation. A copy of a copy introduces even more. So hearing the 6th generation of a recording is not like hearing the original, in the same way that a Xerox of a xerox of a xerox of a photo is obviously inferior to the original. He's hearing that noise. Whereas with a digital recording (or a digitized photo), all those numbers can be transmitted without error and reconstructed to be a perfect reproduction of the original sample, even if the original sample was an inferior copy of the source material.
Don't know if that helps. The more I try to make this description accurate, the more complicated it reads.
