Gregorian Chants

Have you heard of these music? I'm pretty much sure that you most likely did specially if you are a Roman Catholic.  I heard of this angelic canorous song on the latter part when attending mass in the church. It was sung on a head voice. I came across this on a social media and it piqued my interest. Whenever I listen to this, it kind of soothes me and gives me goosebumps.

Pange lingua gloriosia

Tantum Ergo