I spent from about 1988 to 1992 listening to more of this music than just about anything else. I was in love with this music so much that at one point I thought I should just move to Bulgaria and study composition with some of the composers who where writing this music.

https://en.wikipedia.org/wiki/Le_Mystère_des_Voix_Bulgares
http://themysteryofthebulgarianvoices.com/www/