I have found some books unbearable because an otherwise perfectly acceptable narrator got a pronunciation wrong and the word kept coming up. I don't mind it so much if it's in character not to know, but it can be so painful. There was some recent Boston based book—Tuesday Mooney, maybe—where the narrator couldn't pronounce the names of a bunch of Boston-area places and it pulled me out of the book every time. Just go to youtube! You can find people pronouncing the place name!