in case you are wondering where im going with this... mp2 is a much less complicated codec than mp3 able to play on a 486 machine fine... but of course reusing the psychoacoustic model gives mp3s a case of the 'gurgles' (use a vocal remover dsp plug to hear the gurgling front and center on low bitrate mp3) moreso than the codec it was designed for; mp2 ...
i dont count AAC, vorbis, and opus since their increased complexity came with a better model...
just a little historical tidbit for the ears...