Steep High freq rolls offs in mastering - counter-productive?
Just something i thought of the other day when discussing techniques with another Dance music producer, when we were discussing mastering he explained he always rolled off from 17 or so k in his master quite steeply, from memory 26 or 48dB. When i asked him why he didn't know :P. What's the point of doing something if you don't know why.
After 'testing' quite a lot of Dance tracks from all different genre's, the ones that i perceived as sounding dull, less clean and flat to me more often than not had a steep high freq roll off when analyzed, from anywhere between 18 or so down to 15, yes 15 =\. The tracks in question were legitimate WAV final masters.
To me, steep roll offs don't make sense. I've mastered tracks before that had loads of high end energy that was tamed with a subtle high freq roll off, but anything steep to me completely baffles me. Most of the target audience in dance music are younger people too who probably still have pretty good hearing, so to me it's shooting yourself in the foot.
So my question is, is there something I'm missing here? Is there a logical explanation deeming steep lowpassing necessary - especially in WAV masters. I've read and heard that extreme high frequency roll off's may be able to improve the compression result when encoding to MP3 considering there will be less data needing to be compressed, but I'm skeptical and haven't tested this theory out properly myself.