I must say that one of the "Saving Graces" (
oh, for the pun of it ...) of my main BK experience was that it happened in the 80s when music and fashion was mostly certainly at its "Fag End" of the Dark Age (...
no disrespect meant to paul). The BKWSU might have been bad in retrospect but at least it saved me from big hair, power shoulders and other
unmentionables such as marbled denim jeans.
Of the Balkan women's choir, I remember when they hit the world music scene and they are quite remarkable, if we are thinking about the same tradition. I cant explain what they do technically. It appears to create harmonic effects and I think they are now connected to the Orthodox Church of Christianity. I suspect it is an older and more universal tradition though. I found one video clip that sounds almost like chanting 'Om'. Not surprisingly, "open-throat" singing, as it is called, also happens in the Indian sub-continent.
Do you means, these kind of singers? I think the original group/record to make the scene were 'Le Mystere des voix Bulgares' and Bulgarian but its seems a more widely practised style. Quite remarkable. It fluffs up and attunes the aura nicely, which is probably why it is thought of as sacred. For the sake of a quicken the page loading, there is another link,
here or below.