It depends on what "chant" is. If we're talking "Missa de Angelis" or similar, the scales used are familiar as they are derived mostly from "major". Even so the Latin would be a challenge for the uninitiated.
If we're talking true Gregorian chant, that's another animal. Maybe someone would know better than I, but I don't believe much of what we hear are "scales". At least not any that I've known. Also the layout of the "songs" tend to be unstructured and difficult to internalize.
That and if you notice, most chant sounds as if they cloned a monk from 1240 AD and reproduced him to record CDs for us. They all pretty much sing with the same voice and same inflection, no single singer distinguishable from the others. Vibrato is pretty much verbotten on many pieces. Bob the opera singer standing next to Top 40 Tom would cause both to have a bit of re-adjusting to do.
I guess my point to borncatholic was that I don't see a pastor in the average parish being able to announce "hey we're going to Gregorian chant... any volunteers?"
I pinged pyro, he sings the chant. He'd probably have some input on the subject.
bttt
Chant is sung in modes, not keys, but for practical purposes, Chant can be read in "keys." Modality lacks minor/major resolution and modal scales are, therefore, neither minor nor major.
You contradicted my comment about Propers Chant, wherein I observed that singing actually gets easier over time, rather than harder. I suspect that Pyro will agree with me--but hey! I only have about 20 years' practice with Propers chants.
The specific vocal production technique utilized for singing Chant varies from school to school. The best one I am aware of is the one from the West Coast (Roger Wagner/Paul Salamunovich.) You can actually find some Chant examples at GIA Publications (Chicago), recorded by Roger's Chorale...
That vocal technique happens to be identical to the one used by Frank Sinatra (who was trained to sing this way in his Catholic grade-school) and by ALL choral singers who are trained by anyone worth a damn. The point, of course, is to efface the individual's voice--that's called 'ensemble.'
Singing in Latin is no harder than singing in French or Spanish or German, or even vocalese...in fact, Latin is easy to pronouce to an English mouth and is probably easier going than french.
Singing in different languages is not particularly hard.
Latin is a great language for singing. Latin has the ability to take lyrics which would sound trite if translated exactly into English and make them sound wonderful (for a secular example, go check out the translation to O Fortuna in the Carmina Burana, a piece we hear a lot that has great power, but what silly lyrics)because of the lovely alliteration and assonance available, very rich to the ear.
To hear its' power even in repetitious use, we just have to go back and listen to any of the litanies of the saints done during the funeral for John Paul or the conclave. Wonderful power to tune the heart, mind and ear towards heaven.
This is not something we should fear, even if we aren't very fluent in it.
I guess since I grew up hearing Gregorian Chant, it seems perfectly simple to me. But, then, it wasn't exactly real Gregorian. Last summer, I went to Vespers in Latin Gregorian as was able to sight read it, so it wasn't that hard. The intervals are consistant. Other forms of chant can be more difficult until I get a feel for it, but after 20+ years of choirs and choruses, not much that isn't opera (and romantic coloratura at that) throws me.
Seriously, it's the line that's the problem.