I don't think they should be closed, but considering that it could be enough to look the pronunciation reported in a dictionary, should questions about pronunciation be closed using the "general reference" reason?
If the question is "How do you pronounce this?", which is a Poll, then I think so.
But not if the questions are like:
- What is the correct pronunciation of x?
- I've heard two different pronunciations, x and y, what is the correct one?
- What are the differences between the BrE pronunciation and the AmE one for x?
- Are there differences in meaning if I use the alternative pronunciation for x?
- What is the origin of the pronunciation of x?
Just the first ones that came to my mind, in the end, it's always a matter of "being specific".
I'm not sure about "What is the pronunciation for x?", because I've seen it left open before, if I'm not wrong.