Old thread on singing in dialect may be of interest here.

Over the years I've become grudgingly comfortable with my own approach to this: keep the vocabulary, let the words drive the accent if they want to, and don't force anything beyond that. If the dialect in a particular song is too thick, I leave it for someone else's repertoire.

Then again, if I'm actually trying to sing in a different language (French, Gaelic) I do my level best to pronounce it decently, and a song like "Wee deoch an doras" just requires the thickest put-on accent I can manage -- and in that case no one thinks I'm trying to make 'em believe I'm from Glasca. But for the most part I try to be myself and let the song come through on its own.

The result is that I sing AA spirituals like a white southerner. Some are real gems even when sung that way, some I have to leave be.

It would be no less laughable for me to try to duplicate Burleigh's dialect than to duplicate Paul Robeson's voice.

-HM