For heaven's sake, radio classical-music announcers, there is no acute accent in the word Debussy! How many times do I have to tell you? It is not Daybussy. The e in the word is pronounced just as in je. And the stress is on the last syllable: Duh-bu-SSI.
I have been yelling this at the radio for probably 40 years. More important than the question of the consistent mispronunciation is the question of my own annoyance. Why does it bother me so?
It bothers me just as much when people talking about painting say Dégas, not Degas (Duh-GA). There is no accent in his name either and English speakers insist on seeing one there. It is probably because they are trying to sound as French as possible and so are eager to see French accents in French words.
This is probably an example of what linguists call overcorrection or hypercorrection: when people make a grammatical mistake out of fear of making a grammatical mistake. For example, when they say, "Whom is coming to dinner?" or "He offered gifts to you and I." They are saying what sounds to them more proper or fancy, but with no regard for actual grammar. If you think the plural of octopus is octopi, you are overcorrecting: The word's origin is Greek, not Latin. The proper English plural is a simple one: octopuses.
"Between you and I" is often used as an example of overcorrection, but it is a phrase fiercely defended by linguists because it is, they say, an ancient usage and has been repeated to the point of being standard.
Overcorrection also occurs when people get obsessed with a certain rule of language and try to apply it everywhere, even when it seems unnatural. For example, we put an n after the indefinite article "a" if it precedes a vowel: An onion, an enemy. Does a y count as a vowel in this case? Do we say "an youth"? No, because the y creates its own stop after the vowel. We only use these tricks when they are useful, when they make speech easier. How about "an university"? Sounds wrong, doesn't it? It is much more natural to say "a university." That is because the first sound of university is much like a y, and provides a glide not unlike a consonant sound. If we apply rules single-mindedly in all cases, we end up sounding pretentious.
The humorous T-shirt that says "I am for whomever beats Harvard" is actually boasting of incorrect grammar: In this case, "whoever" would be the subject of the predicate "beats Harvard." That is overcorrection.
But what about foreign names and words – how correctly must we pronounce them before we become pretentious ourselves? Our language has a glorious history of absorbing foreign words, and of course we anglicize them to one degree or another. Most people say lingerie in a way that has no bearing on French pronunciation (you probably say something like lonzheray, right?) and that has become standard English pronunciation. Lingerie, like ballet and rendezvous, is now an English word. Proper nouns are also routinely anglicized: we say Paris, not Paree, and Jacques DERR-ida, not Derri-DA.
But many foreign words still occupy an uneasy space between the languages, and their pronunciation tends to vary with social class. It bugs me inordinately when people say brushetta instead of bruschetta (with a hard c), but that's pure snobbery, I'll admit. When you say, "He ate the meal with gusto," you probably say the last word as an English one (with the u as in bust), but you do have one friend who insists on saying "goosto" after doing a semester of art history in Florence. How you pronounce espresso (with an x?) is also an indicator of social class.
How far do we go with our fidelity to foreign sounds? Our pronunciation of Chinese names will always be an approximation, that is to say a deformation. We seem to crave absolute fidelity only to European languages because Europe is where erudition and sophistication are seen to come from. So who is the greater snob: the overcorrecting radio announcer, who adds a Frenchified é to a name in order to sound more European? Or is it actually me, the pedant, who demands actual familiarity with foreign languages?
Other language speakers distort English names as well. The famous financier and gambler, John Law, whose investment schemes ruined the French economy under Louis XV, was called John Lass in French histories for decades, because of a misreading of his name when written in cursive (a handwritten w can look a lot like two s's), and simply because there were no w's in French at the time. The French don't care: They say what they want.
It is possible that Débussy has become the current English pronunciation of this internationally loved composer's name, and that I need to accept that and stop screaming at my radio, which can't hear me anyway.