[pmlnr]

Does a 1% compression jpeg _supposed_ to be distinguishable from the orginal? Probably not, until it goes into a 4m x 3m print.

MP3 does the same to sound that jpg does to colour: those similar enough become one. And it also cuts off the "inaudible" sounds. If you open a spectogram, 320 still cuts at 20khz, whereas most CDs have until 21-22khz - because there are people out there who hear those sounds. (There are some "ultrasonic" cat & mammal scare away devices, which I hear, and they are literally painful to me.)

But answering your question: no, the goal was to have a good enough, but massively smaller file. The goal was never not to be possible to tell them apart.

FLAC compresses a CD to roughly half of it's size - that's already a big win.