Lots of people can only hear to about 15 KHz.

That wikipedia link is pretty good. http://en.wikipedia.org/wiki/Mp3 They point out that at a certain quality level, the mp3 format achieves "transparency" meaning the listener cannot tell the difference between the mp3 and the original. They say that very few people can detect an mp3 at 192 kbps and above. Maybe a power spectrum graph will show a difference but people cannot.

Just rip a CD track to mp3 at various bit rates, and then load the mp3 and the WAV file into the virtual CD decks in a program like Traktor to compare the two. Traktor lets you loop the music at a certain spot for a good comparison and it has a crossfader so you can quickly switch between decks. Or maybe load the WAV and a mp3 into a couple of real CD decks and do a comparison.

Personally I can't tell the difference between the WAV and a 192 kbps Lame mp3 and a VBR Lame mp3 (alt prest standard). Transparency has been achieved. My tests, which are just informal comparisons, are done with a 24 bit Echo sound card, Sennheise HD280 headphones, and Paradigm Phantom and Titan speakers connected to a Denon receiver. Also I've done quicky tests with Mackie SRM450 speakers (12" self-powered) and a medium quality 6000 watt club system.

Maybe if I had really good monitor speakers I could detect a 192 MP3. But I'm satisfied that my personal mp3 collection is good quality.

theres deffo some well encoded high bitrate mp3s where i just cant tell the difference at moderate to loud levels in my room. dunno about a club though. that said if you go an run a wav from a cd and stick a parametric EQ on it - whack the last bar all the way up to 16,000 and hard shelf it off. keep lowering and raising it and you will notice a difference - especially to parts of the hihats.

but your ears kind of adjust to the sound over time so it becomes difficult to distinguish unless you are doing side by side comparisons like this.