I've been reluctant to chime in, because I've expressed my (unpopular) views on this topic many times before.

Also, this seems to be a controversy pursued much more passionately on one side of the Atlantic than the other, and I live on the side where we're not too worried about this.

Perhaps one reason is that folks in the UK are so very conscious of the many different accents that still survive in different geographical areas (and in different social classes, too), while in the US, we are much further along the road to homogenization. We still have regional accents, to a degree, but they're dying out as our people become ever so much more mobile, and as a nationwide media market exerts an ever-increasing degree of influence upon us.

All that said, let me posit what I believe to be fairly universally true: The song and the musical form (or "genre") has a whole lot to do with determining a singer's pronunciation of lyrics.

Now, there's a big difference between a tasteful and sympathetic approach to a song's native and built-in "accent," on the one hand, and a slavish and ill-informed attempt at imitation of persons of a linguistic subculture different from one's own.

For example, there are any number of excellent blues/R&B singers who are white Americans and white Britons, and what they are doing is far removed from the blackface/minstrel-show entertainment of an earlier generation. Any halfway decent interpreter of the blues will sing in his/her "own voice," but at the same time will employ a set of standard, traditonal vocal sounds that should not be considered imitations of Black American speech, but rather as integral sonic features of a musical tradition.

Let me offer an example from outside the world of music and song to demonstrate that an element of "accent" can be built into a given bit of lyric, so that it can only be uttered using its own "native" vowel and cononant sounds. Find a copy of the collected works of John Milllington Synge, or of any one of his plays ~ "Playboy of the Western World," or any of the one-acts.

Read that material out loud ~ it's impossible not to employ a bit of an Irish accent or "brogue." Much of this effect is undoubtedly due to the rhythms and lilt of the poetry; word-order within sentences must be part of it, too. I don't claim to understand exactly why it is that a composition of words on a page can dictate the manner in which they are pronounced aloud, but it certainly seems to work that way, whether or not we understand why.

Now, the way that you or I read Synge aloud may not exactly match the true accent of any particular region or subculture in Ireland (although Synge is probably forcing us to speak more-or-less like the residents of his beloved Aran Islands). But we are going to adopt certain dipthong sounds and certain rhythms that are common to all the various regional accents of Ireland.

If any of us were to portray one of these characters on stage, we'd be expected to speak in a manner that is NOT precisely our own native accent, but not blatant overstated "stage Oyrish," either. Any halfway decent actor, even an amateur, will find a way to use his own voice, certainly, but to add a layer of interpretation in the form of pronunciations that differ from his everyday offstage speech.

I would argue that the same goes for performance of songs, not all songs certainly, but many songs that are identified with a particular culture or that are typical of a given style. I would tell anyone wondering whether or not to sing a particular song, or how to pronounce its lyrics, just to trust your instincts ~ and also, if there's any doubt, to "try it out" with a limited audience of trusted friends and advisors before going more widely public.

If you have grave doubts that you can perform a given number adequately, you may be right ~ your own ambivalent feelings will be evident in your performance. There is always a way to sing "naturally" and "in one's own voice" on the one hand, and to use pronunciations appropriate to the song on the other. However, there's an art to this. Ask yourself if you're capable of this particular tighhtrope act; also ask yourself if you feel capable of learning. I'd say that we're all capable, but unless you start off with a bit of confidence, you won't be able to do it.