Fellow followers of Latin stackexchange! I hope you have all had a happy Christmas (or, if you do not celebrate Christmas, a happy holiday time).
I'm not particularly versed in musical tradition, but I've been aware for some time now that the modern de-facto standard for pronouncing Latin in singing is what is commonly referred to as the "Ecclesiastical" pronunciation. Now, this makes sense in a purely Roman Catholic context, but it seems to be standard quite outside of that. So, in the well-known Christmas carol "Angels we have heard on high", the Latin phrase Gloria in excelsis Deo is pronounced (as far as I've observed) more or less as [ɡloːːːːː::::ria in ɛksʧɛlsis deːoː]. But, why?
My understanding (perhaps erroneous) is that the Italianate Latin pronunciation became standard for the RC church only in the 19th century, so why has it now become normal for singing in Latin universally, outside of a RC context? Quite apart from the Christmas-tide "gloria in excelsis Deo", I was recently hearing a rendition of Carl Orff's musical version of a Latin mediaeval poem from Carmina Burana, O Fortuna, and was struck by the consistent modern Ecclesiastical pronunciations, e.g., glaciem as [ɡlɑʧiɛm]. Assuming that a restored Classical/republican pronunciation of [ɡlɑkiɛm] would be considered inappropriate for the time-period, and that the Carmina Burana was a collection of a German mediaeval Latin poems, wouldn't [ɡlɑtsiɛm] be more appropriate? (At any rate, I find the Italian pronunciation rather off-putting in the context.)
A final postscript: although what I've heard is that excelsis is pronounced in the Christmas carol is [ɛksʧɛlsis], wouldn't [ɛkʃɛlsis] be the "correct" Ecclesiastical pronunciation?