If you want to hear the incredible "singing in fifths " there can be no finer sound than that of the Icelandic group "Embla" I heard them at a Baring Gould Festival and was totally blown away by the amazing sound of Didi,Kris,Bowra and another woman singerThis has ,for me been an enduring memory.
If Ive put this to the wrong post Sorry!
The prog was pretty good