I was listening to these Hymns, and some of them are called 'Zenemmy' Chant. Another is called a 'Georgian' Chant. There is of course the Byzantine Chant.
All you have to do to find out about ANYTHING is google it, or look it up in wikipedia
You can download a whole CD of the most beautiful Russian chants i've ever heard:http://www.3saints.com/music.html
One of the most outstanding one is called the 'Zenemmy' Chant. Look it up: http://en.wikipedia.org/wiki/Znamenny_chant
I can't believe that CD is in English!
Recorded in 1996.