I respect it when I hear someone clearly attempting a word they've only seen written

I pronounced it the same way, until whichever book has that scene with Viktor Krum pronouncing it wrong and being corrected. I believe the story goes that Rowling included that scene because there were so many of us doing it.

That's how we pronounce it in Spain! Actually the H has no sound, so she's just "er-me-on"

So how is it pronounced?