>>O words spelled with ao<<

From Wordnet, Princeton U. (Sorry, I can't give a url, I got it from Mac Sherlock using the dictionary channel. There is a good deal more, there. If anyone's interested, I can post it or PM it.):

The name is a compound, as some think, of the words Ra, the "sun" or "sun-god," and the article phe, "the," prefixed; hence phera, "the sun," or "the sun-god." But others, perhaps more correctly, think the name derived from Perao, "the great house" = his majesty = in Turkish, "the Sublime Porte."

If it's a compound, the 'a' would have been pronounced. Unfortunately, I don't know how to spell Paraoh in Hebrew (!) but I wouldn't be surprised if there were an alef of an ayin there, which might also have been pronounced as a gutteral 'ah'.