Human hearing beats sound’s uncertainty limit, makes MP3s sound worse

I think everyone also needs to consider that the "psychoacoustic assumptions" made when MP3 was developed were generalized (a lot like the compression algorithms used for JPG pictures). This means that they were designed to work well on most music, for most listeners, most of the time. I've certainly heard low-rate MP3 files that sounded very good (and indistinguishable from the original). I've also heard specific pieces of music that always sounded bad when converted to a MP3 (no matter what bit rate or encoder). It seems obvious to me that certain sounds, or combinations of sounds, fail to "fit into the model" that was used when MP3 was developed (they probably have too many disparate tones - disparate in time or frequency - and the encoding algorithm is unable to find a way to apply the encoding algorithms to successfully reduce the size while ensuring that all the removed information is masked). A similar thing happens with JPG pictures.... certain originals contain elements that the process doesn't work well on.... and so the result is poor. [With JPGs, they work well on continuous tones, like portraits, and very poorly on artwork with lines, like cartoons or text. You can easily JPG a portrait to 10x smaller with no visible loss of quality, but text usually shows noticeable degradation - under magnification - even when JPGed at full size.]

Of course, lossless files have the huge advantage that, since nothing has to be omitted, you don't run the risk of omitting something that cannot be masked.....