The Orthodox don't allow musical instruments in their liturgy and ritual because they believe that God created the human voice as the ideal musical instrument.
I'Ive also Googled Gregorian Chants which are a Capella chants of Latin prayers and readings. These too are very powerful sacred chants. However, I must say I favor the rich and moving Orthodox chants much more. Give them a try. I'm sure you will be moved and feel a deep and abiding reverence.
The proof of the pudding is how the music of the gospel plays out through a life, and the Lord could even use kazoos to that end without losing holiness. I aver that we need to evaluate all means in context.